I don't have any experience with speaker kits per se, but I've purchased drivers from http://www.northcreekmusic.com/. Their kits are very well respected. The owner, George Short, has worked for some impressive companies like AR and Apogee. Check out their web site.
http://madisound.com/about/kits.php is another option, but if I were in your shoes, I'd look at North Creek first, if for no other reason than resale value.
http://madisound.com/about/kits.php is another option, but if I were in your shoes, I'd look at North Creek first, if for no other reason than resale value.