Several places offer linux-compatible laptops without operating systems (www.idotpc.com, www.gearzoo.com
). Check Lindows.com website for a list of places that sell Lindows laptops. If they work with Lindows, they'll work with any Linux.
Another option is to buy used. A great site is retrobox.com they have used Dell and IBM latops without operating systems for less than $1000 US.