The word "insane" is key here. In normal usage it just means mentally ill. But in modern parlance it can mean that as non-literal insult. But it can also mean irresponsible, unreasonable or very foolish, as in to apply irrational judgement. This can informally describe scenarios that are merely irresponsible, wacky or wild. I credit Crazy Eddie, the actor with propagating that last use case into popular parlance. True to form, Eddie was actually New York radio disc jockey: Jerry Carroll.
The chain of electronics stores is long gone today, but the real Crazy Eddie, Eddie Antar, started the business in 1971 in Brooklyn, NY with his brother Sam. Their connection to Jerry was happenstance, but it made Carroll into the defacto face of the business. In 1972, The Antar's bought airtime on 101.9 WPIX in New York. They went cheap and went for a live read. The DJ was "Dr. Jerry" Carroll, who ad libbed the shop's slogan into a primal scream "...His prices are INSAAAAAANE!" Eddie Antar loved it; he called the station and told Carroll to use that delivery every time. Carroll obliged and continued the style as they launched TV spots in the 1980s.
At its peak there were 43 Crazy Eddie stores earning more than $300 million in annual sales. Then came the fall. Eddie was very naughty. He was indicted for tax fraud, overstating income, bogus asset valuations, stock dumping, overstating insurance claims, debit memo fraud and the topper... money laundering. More here. Eddie fled the country and had to be extradited from Israel to stand trial. The board of directors revolted and the whole Antar family was cut out of the business. In 1989, the company declared bankruptcy and was liquidated.
Fresh from prison, Eddie returned to the company in 2001 which then was only an online store. Jerry Carroll was hired a third time to do its advertising. But somewhere between 2004 and 2004 it sank for good. The Crazy Eddie trademark was bought by the Trident Growth Fund. In July 2006, Trident attempted to auction the brand and the domain name crazyeddie.com on eBay, but had no takers.
The rise and fall of Crazy Eddie overshadows the rest of Jerry Carroll's radio career. Before the Antars, Carroll was "Dr. Jerry" and was "prescribing your rock ’n’ roll!” on WPIX. Born in 1947, Carroll was a young DJ at 26 when he met the Antars. More here. There is an apocryphal story of a WNYU student DJ also named Jerry Carroll who co-hosted a record hop with Bob Lewis from WABC-AM back in 1966. I like to think it's the same Jerry Carroll. Regardless Carroll was on WPIX thru at least 1977 when he switched to afternoons after hosting the nightly show "Disco 102." He had previously been on WVIP, and WRNW, so the WABC story, fits nicely.