The Battle of Waterloo (on June 18, 1815) was frequently reenacted, with a showman explaining the action. The story goes that confused patrons asked, “Which is the Duke of Wellington? Which is Blücher?” The showman replied, ““Whichever you please, my little dears. You pays your money, so takes your choice.”
 
The story has been cited in print since at least 1826, with the showman saying, “Which you please!” The saying “you pays your money, so takes your choice” has been cited in print since at least 1839.
 
New York (NY) Times “On Language” columist William Safire observed, in 1988, that the saying means “the right of choice is to the buyer.’’ However, modern interpretations make the saying a simple rebuff of a complaint,  similar to “you made your bed, now lie in it” and “if you don’t like it, you can just lump it.’‘
 
   
Wiktionary: you pays your money and you takes your choice
Proverb
you pays your money and you takes your choice
1.Each person should make their own decisions.
“You can get there by bus, or train, or taxi. Whatever. You pays your money and you takes your choice.”
Usage notes
This phrase is almost always pronounced in the ungrammatical form: you pays and you takes.
 
Cambridge Dictionaries Online
You pays your money and you takes your choice/chance.
informal saying
You are responsible for your decisions and cannot blame anyone else when what you have chosen is not successful.
 
Wikipedia: Battle of Waterloo
The Battle of Waterloo was fought on Sunday 18 June 1815 near Waterloo in present-day Belgium, then part of the United Kingdom of the Netherlands. An Imperial French army under the command of Emperor Napoleon was defeated by combined armies of the Seventh Coalition, an Anglo-Allied army under the command of the Duke of Wellington combined with a Prussian army under the command of Gebhard von Blücher. It was the culminating battle of the Waterloo Campaign and Napoleon’s last. The defeat at Waterloo put an end to Napoleon’s rule as Emperor of the French and marked the end of his Hundred Days’ return from exile.
 
Google Books
Lessons in criticism to William Roscoe, Esq;, F.R.S., member of the Della Crusca Society of Florence, F.R.S.L.: in answer to his Letter to the Reverend W.L. Bowles on the character and poetry of Pope ; with Further lessons in criticism to a Quarterly Reviewer
By William Lisle Bowles
London: Hurst, Robinson
1826
Pg. 78:
When a rustic urchin, with intense admiration, was looking through the small window of a peep-show, the “master of the magic show,” pulling a string, cried, “There you see the DUKE OF WELLINGTON as large (Pg. 79—ed.) as life; and there, the King of Prussia!!” “Which is the Duke of Wellington?” inquired the eager, and almost breathless, young Somerset rustic! “WHICH YOU PLEASE!” said the man at the string, without moving a muscle!!

Google Books
28 June 1834, Figaro in London, pg.104, col.1:
A scavenger employed for the purpose turned up the other day an old copy of The Battle of Waterloo, which, soiled as it was by contact with old bits of mutton fat, pea-pods, oyster-shells, and cabbage-leaves, was shoved into rehearsal by way of novelty. Cartlitch still flares up as Buonaparte, or somebody else, though it does not matter which is which, for as far as identity goes, the thing is, like Lubin Log’s sixpence, quite hoptional. Ducrow would say of his actors as the showman said of his painted figures, on being asked “Which is Blucher, and which is the Dule of Wellington?” every one knows the old reply, “Whichever you please, my dear,” and such (as far as distinction in his actors goes) such must be the response of the dandy dog’s-meat man!
   
Google Books
Young Gentlemen of the Nineteenth Century
Brighton: J. Taylor
1839
Pg. 1:
Most of our readers doubtless heard the story of the showman at the fair, who, on being requested to state which amongst a number of figures in his picture of the Battle of Waterloo, was intended to represent the great Emperor himself, politely rejoined, “Whichever you please, ma’am; you pays your money, so takes your choice.”
 
Google Books
July 1841, Bentley’s Miscellany, pg. 365:
The only other show was a pictorial representation of “say ingagements,” and “the battle of Waterloo.” Such an admixture of soldiers and sailors fighting together was never seen before. The old joke was really verified: “Look to the right, and there you see Napoleon Bonapartee leading the French army. Look to the left, and there you see the Marquis Wellesley beating him from the field.”—“Which is Napoleon Bonapartee, sir? and which is the Marquis Wellesley?”—“Whichever you please, my little dears; only don’t breathe on the spy-glasses.”
 
Google Books
3 January 1846, Punch magazine, pg. 17:
THE MINISTERIAL CRISIS.
SHOWMAN.—“On your right you will perceive a Prime Minister a Bolishing of himself. And over your left is another Prime Minister a Bolishing of the Corn-Laws.”
MASTER JOHN BULL.—“But which is the Prime Minister?”
SHOWMAN.—“Whichever you please, my little dear. You pays your money, and you takes your choice.”
 
Google Books
Lectures to the Men of Liverpool
By Hugh Stowell Brown
Liverpool: Gabriel Thomson
1860
Pg. 19:
This. however, I beg of you to observe, is the grand peculiarity of the book of Fate—that it will return to your question any answer you choose; it is like the showman, who, when asked, “Which is the Duke of Wellington?”—very properly replies, “Which you please; you pays your money, and you takes your choice.”
   
New York (NY) Times
ON LANGUAGE; You Pays Yer Money
By WILLIAM SAFIRE
Published: February 28, 1988
(...)
Mark Twain used the saying in 1884, at the end of chapter 28 of ‘‘Huckleberry Finn,’’ I am informed by Richard Bliss of New York City: ‘’. . . here’s your two sets o’ heirs to old Peter Wilks - and you pays your money and you takes your choice!’‘
 
The origin, as dozens of other Lexicographic Irregulars stepped forward to say, is British, probably Cockney. The first time the saying saw print was in an 1846 Punch. A cartoon entitled ‘‘The Ministerial Crisis’’ has a showman telling a customer, ‘‘Which ever you please, my little dear. You pays your money, and you takes your choice.’‘
 
The phrase still means ‘‘The right of choice is to the buyer,’’ or a more sophisticated ‘‘Power belongs to those who have paid their dues,’’ but a much different sense has emerged.