Sellathon (sell + marathon)

A “sellathon” or “sell-a-thon” (sell + marathon) is an event that retailers often hold featuring discounted products. “Sellathon” has been cited in print since at least 1952 and the term has frequently been used by car dealers.
 
Another term for a “sale marathon” is “saleathon.” Similar sales terms include “saleabration” and “sellabration.”
   
 
16 December 1935, The Evening Tribune (Albert Lea, MN),  “School Notes,” pg. 6, col. 6:
Our race in selling Christmas Seals is in favor of Sellathon so far. They are 16 stamps ahead of Workathon.
 
20 November 1952, The Capital Times (Madison, WI), pg. 19 ad:
Visit our Grand Opening “SELLATHON”
(I.G.A. Market—ed.)
 
12 March 1954, Boston (MA) Daily Record, pg. 60, col. 2 ad:
GIANT
SELL-A-THON
(Corcoran’s auto dealership—ed.)
 
14 January 1955, San Diego (CA) Union, pg. b-15, col. 5 classified ad:
UNITED
AUTO SALES
—WATCH OUR—
T.V. SELLATHON
 
25 June 1955, Albuquerque (NM) Journal, pg. 14, col. 3 classified ad:
ALBUQUERQUE
MUSIC CO’S.
GREAT
Sellathon
 
29 March 1967, Dallas (TX) Morning News, pg. D6, col. 1 ad:
SPRING SELL-A-THON
(Champ Davis Motors—ed.)
 
Google News Archive
15 November 1978, Youngstown (OH) Daily Vindicator, “Inside Labor: More Pie for Teamsters” by Victor Riesel, pg. 85, cols. 2-3:
Mr. Carter’s proposals, now on that road in what’s being called a national “sellathon,” would fail to stop inflation. No doubt about it.
 
Google News Archive
27 March 1981, The Gazette (Montreal, Quebec), “Illinois sues Toyota,” pg. 33, col. 1:
SPRINGFIELD, Ill.—Illinois Attorney General Tyrone Fahner filed suit against Toyota Motor Co. yesterday, charging the Japanese automaker is deceiving Illinois residents with its Toyota ‘Sellathon” commercials.