Carpet is about $90 new and headliners are about $50. those are both easy to find in many catalogs
All plastic parts can be scuffed and painted with paint made specifically for that. I have used it on a few small interior parts to see what it will look like and it turned out well.
They also make paint/dye for the vinyl (sp?) parts of the dash and door panels.
besides the seats, that pretty much covers everything, and wouldnt be too expensive to do. Unless you buy those FR500 seats
good luck with it,
-Drew