KT Ordnance sells 1911 frames. Link is above, and prices are posted, don't know about current availablility. His frames are machined from 2 blocks of steel and brazed together. I have one of his SIG P228 frames and a 1911.
Also,
www.tanneryshop.com, but I don't know what they have in stock. (Owner was called up for Iraq, but National Ordnance is handling the business until he returns. Phone number is on Tannery Shop's home page. I believe they carry both forged and cast frames.
You don't need to bring the slide, although bringing it won't hurt. If you don't bring it, you may have to file/lap the rails a little to fit, which isn't a bad thing.
I've been to a couple of his BBQ's and bought a few frames from him and machined them. Not related to the business...just passing the word.