“Buccaneer” sounds like “buck an ear,” leading to the joke:
 
Q: How much does a pirate pay for corn?
A: A buccaneer.
 
“Buccaneer is too much to pay for corn” was cited in print in 1941.
 
   
2 July 1941, Portsmouth (OH) Times, “Pete Minego’s Sports Gossip,” pg. 16, col. 5:
Buccaneer is too much to pay for corn.
 
Google News Archive
17 August 1941, The Spokesman-Review (Spokane, WA), pg. 2, col. 1:
Corny Joke
If any one asks you how to pronounce the word “buccaneer,” don’t tell They’ll just say that It’s an awful price to pay for corn
 
Google News Archive
15 October 1942, Inwood (IA) Herald, pg. 2, col. 5:
Ain’t It?
Gob—What is a buccaneer?
Pal—A buccaneer is an awful price to pay for corn.
 
Google News Archive
23 October 1943, The Evening Citizen (Ottawa, Ontario), pg. 15, col. 6:
How Are You At Cracking Nuts?
Riddles sent in by Jean Lothian, 35 Findlay Ave., Ottawa.
(...)
What is a buccaneer? Too much to pay for corn (buck-an-ear).
 
Google News Archive
26 November 1957, Sarasota (FL) Herald Tribune, “Sarasota Scene” by Stan Windhorn, pg. 4, col. 7:
And finally Jim Shutts, who, incidentally, can stage a fine fish fry, stopped by to inquire, “Do you know what a buccaneer is?”
 
We didn’t and Mr. Shutts ran for cover after saying,“A uccaneer is too much to pay for corn.” .
 
Google News Archive
12 December 1981, The Free Lance-Star (Fredericksburg, VA), “A dictionary full of daffiness” by Gyles Brandreth, Town &  Country Magazine, pg. 13, col. 2:
buccaneer: too much to pay for corn
   
Google Books
The Railroad Yardmaster
Volumes 26-29
1944
Pg. ?:
Rank Piracy
Son: “Pop, what is a buccaneer?”
Pop (engrossed in newspaper) : “A buccaneer is an awful price to pay for corn.”
 
Google Books
50 Great Monologs for Student Actors:
A Workbook of Comedy Characterizations for Students
By Bill Majeski
Colorado Springs, CO: Meriwether Pub.
1987
Pg. 128:
A patron asked, “What’s a buccaneer?” Retorted Madeline: “A buccaneer is a very high price to pay for corn.”
 
Twitter
Becky McCray
‏@BeckyMcCray
How much was the pirate corn? A buccaneer!
12:45 PM - 19 Sep 2007
 
Google Books
Lots of Jokes for Kids
By Zonderkidz
Grand Rapids, MI: Zonderkidz
2015
Pg. ?:
How much does a pirate pay for corn?
A buccaneer.
 
Twitter
Siegel’s Farm
‏@SiegelsFarm
It’s “Tell an old joke Day”.  How much does a pirate pay for corn?
A buccaneer!
What’s your favorite old joke? http://fb.me/7t1OJDs56
8:14 PM - 25 Jul 2015