It wasn't worth $20,000 when I bought it many many years ago! It's a 1934 Gibson 'The Jumbo.' (They just called it 'The Jumbo' because prior to then they'd never made any 'jumbo-sized' guitars.) I bought it in a pawn-shop for about $350 way back then, as just an 'old used Gibson acoustic' instead of a 'rare vintage collectible' guitar. ($350 was a lot for an 'old used guitar' back then before so many guitars started becoming highly collectible. And $350 back then, adjusted forward for inflation, is the equivalent of close to $4000 in today's dollars.) Since 1934 was in the height of The Great Depression not many people could afford to buy a new Gibson and so not many were ever made.
It really is a tremendous guitar, even my vintage J-45 or a Martin D-45 doesn't come close to matching either its tonal-quality or power.
Gibson made what they called a "1934 The Jumbo 75th Anniversary Re-Issue" about ten years ago. I tried one out in a guitar shop, and while it was a really nice guitar in both playability and sound, it was no match compared to the original. (I was considering buying the newer one and had my original with me for comparison when I tried it out and a few people listening as well as the sales-guy all agreed. When I was done playing a few of the same tunes on each, one younger guy who'd been listening said "That new one ain't shit compared to that old one." )
Several years ago I'd sent Adam from GTU (adds), who is a luthier, specifications, dimensions, tracings, internal bracing info and templates I'd taken from my guitar and since then he has made several guitars using that information. He says they're really tremendous guitars.
Just in case anyone is interested and doesn't want to spend $20,000!