Don't buy the Ebay manuals, the seller steals the data from one of our guys who puts a LOT of time and effort into the CD sets. Download it free if you don't believe in paying for other people work, but don't pay anybody on ebay for it.
The good set of CD's, which I think you can get cheap enough from
Home - 928's R Us Porsche Parts Store includes line drawings that most local copy/print places can print in large format.
Four levels of parts prices, buy a donor car, buy parts from somebody else with a donor car, buy used parts from one of the 928 dismantlers like
928 International |Porsche 928 Parts | New, Used and Rebuilt , new parts from one of the 928 vendors (oops fifth level parts from dealers). It is always a good idea to ask here before buying parts if you have any questions about the part or the best vendor.
$5k to $10k should buy a good 5 spd early 928, but don't get hung up on price, purchase price will soon fade compared to ownership (cost and pleasure). What you need to do is have some cash ready and jump on the first NICE 928 that suits you, pretty much regardless of how good or bad of a deal it is unless the deal totally sucks and won't negotiate, then just wait for it to drop.