If you have all the trim pieces or at least most in good shape then the complete interior is worth more than just seat skins and door panels, particularly if somebody is trying to switch interior colors.

I would say 300-400 would be a quite reasonable baseline and 600 is reasonable if you've got everything in great shape and find somebody wanting this color. Condition and completeness are the key points, though it may be faster to just sell the skins...

Oops, I just noticed how old this post is.