“If you can’t pay cash, you can’t afford it” is a money saying that has been printed on many images. The adage is popular with those who don’t like borrowing money or using credit cards.
 
Origin of the saying is unknown. This was printed in the story “Deferred Payment” by Burt Leyson, in the Daily News (New York, NY) on October 17, 1933:
 
“Henry Parsons was not a penurious man but he was inclined to be saving of his money. More, he had a peculiar, old-fashioned outlook which caused him to look with disfavor upon buying anything unless he paid cash. ‘If you can’t pay cash, you can’t afford it!’ was his way of putting it.”
 
 
17 October 1933, Daily News (New York, NY), “Deferred Payment” by Burt Leyson, pg. 33, col. 1:
Henry Parsons was not a penurious man but he was inclined to be saving of his money. More, he had a peculiar, old-fashioned outlook which caused him to look with disfavor upon buying anything unless he paid cash. “If you can’t pay cash, you can’t afford it!” was his way of putting it.
   
2 May 1951, Honolulu (HI) Advertiser, “May’s Market Basket” by Eleanore Terry Mason, pg. 2, col. 1 ad:
If you can’t pay CASH for it, you can’t afford it!
Our Dad used to say that. He meant what he said, too.
 
20 November 1963, Los Angeles (CA) Times, “Man Learns All About Imperative Credit…!” by Matt Weinstock, pt. 2, pg. A6, col. 4:
A man I know doesn’t believe in what he calls “the dollar a week economy.” His philosophy is that if you can’t pay cash for something you can’t afford it. Clearly he is a throwback to Neanderthal times.
       
9 December 1963, The State (Columbia, SC), “Bob Talbert At Large,” pg. 1-B, col. 1:
A fellow I know doesn’t believe in the “dollar down, dollar a week” economy. To him lay-aways are strictly taboo. He feels if you can’t pay cash, you can’t afford it.
   
28 March 1976, The Sunday Star-Bulletin and Advertiser (Honolulu, HI), “Their First Home by FHA” by Kathy Titchen, pg. F-1, col. 4:
“I’m a good economizer,” she said. “and I have no other debts. I even bought my car for cash. I always say, if you can’t pay cash you can’t afford it. But it’s different with a home—most of us can’t save that much cash.”
 
23 November 1980, Atlanta (GA) Constitution, Ann Landers syndicated advice column, pg. 5-F, col. 1:
DEAR ANN LANDERS: (...) Urge all your readers who are paying with plastic to stop it immediately. Tell yourself if you can’t pay cash, you can’t afford it. If you want it badly enough you will save for it. (...)—No Interest.
     
Google Books
Europe;
On Top of the World
By Michael Gow
Sydney, Australia: Currency Press
1993
Pg. 48:
‘If you can’t pay cash you can’t afford it.’
 
Twitter
Jon Andrews
@Jon_Andrews
To Whom it may concern, IF you can’t pay cash you can’t afford it.  Debt is DUMB!
5:49 PM - 12 Nov 2008
 
SeedTime
25 Quotes that will change how you look at money
SAVE MONEY / OCTOBER 15, 2016 by DAWN
(...)
“If you can’t pay cash, you can’t afford it!