I hand-built my first PC (and all since, excepting laptops and most of those I've tinkered with). I got the money for it by selling off my A1200 030/28 with 4mb RAM and a 60mb HD and a 1084s monitor along with boxes of software. I think I got around $450 for that. The deal was a wash: I got a 486/100 with 8mb RAM, a 170mb hard drive, CD-ROM, VGA monitor, 1mb Trident ISA video card, mouse + keyboard.
I jumped because C= USA had died, and there was a slew of great PC games already on the horizon that the Amiga would never have: I have never had interest one in platformers, side-scrollers, etc.
While I can't speak for bang/buck at the time, I also wasn't waiting around for someone to "maybe someday" come up with a Doom-like game or hoping for some miracle whereby C= (Canada, UK, Australia, depending on who you talk to) would save the day. Or Escom, or VisCorp.
Also? When I was shopping for parts for the last upgrades I ever did to my Amiga my PC-using g/f at the time stopped me from shopping in AmigaWorld - in 1993 or so the 60mb HD and 4mb SIMM I put in the 1200 were way, way, way more expensive through Amiga retailers. I got 'em through PC vendors in Computer Shopper and saved probably close to $100 on the deal. It seems to me there was always an "Amiga Tax" involved in buying from Amiga vendors.