you got me on the battery relocation. i had already done mine for handling reasons so it wasn't that big of a deal. i got my turbo and dp less than a year ago so i know they are still available. as far as the price you need to go here:
www.arfabrication.com. ask for howard. he is the local speed shop guy around my town. i found him because he has an awd dyno. he sells hundreds of pte turbos a year and he smokes most of the syty vendors by a lot... sorry guys. he is on the next level as far as tuning. remember when ford had the problems with the cobras not making enough power? they came to him. he also has one of the fastest honda civics in the country and is the only person who REALLY knows the subaru engines. i recommend you give him a call and see what he can do for you.
as far as the converter, injectors and plumbing this is something i believe you should do anyway on an old truck. i guess everyone's goals are different though. good luck!