There is a yard here in northern CO that sells them. Jeeps Unlimited. Off the top of my head I believe they are in Erie, CO
I actually bought a transmission off of them last year. Unfortunately, from what I've seen, they sell mediocre frames for $3200. While I'm fine with paying extra for an extra nice frame, I'm not fine with getting ripped off (the going rate on craigslist is around $1500 for a mediocre frame). Obviously a Jeep only junkyard is going to be a bit more expensive than craigslist, but over twice the price is a bit excessive to me.