I wish I knew more about color matching and what hardware would be right for that type of thing. Most places I've worked, color matching on a proof wasn't a "big deal" and the clientele were always informed that color on a proof would not necessarily match the final printed piece off the press. Basically the proof was just to give the client a general idea of what the final piece would look like.
As far as color laser printers go, however, I've used 2 pretty decent ones in my (brief, 6 yr) career. At my first job in the field I proposed an HP 8550N color laserjet. They liked my proposal and purchased it. It prints both Letter and Ledger sizes as-well as other stock. I believe it was in the $5k-$6k price-range. Very speedy printer, which was exactly what that job needed. It was thier first color printer, and they needed something so the artists wouldn't need to mark-up color breaks on black and white proofs. The printer was almost the size of a small copy machine and had wheels for moving around (if needed).
My current job uses an Oki color laser printer (as I've only been here a few months I forget the exact model). It's also quite fast, but not as large as the HP I mentionned above. It can also print letter and ledger sizes as well as special stocks if needed. I believe someone mentionned it was in the $5k range.
Again, the two I've mentionned are workhorses and I have no idea how well they work in an environment where color matching is paramount. I can definitely say that with enough memory and drivespace (both printers have an internal hard drive for downloading stuff to, like fonts, etc.) they are fast though. Just remember if you need speed from the thing, try to pack as much RAM as you can into it.
MikeM