It's hard to answer your question - you have to decide what you want and what you will use the car for. If just putting around town then the I6 will be fine. If you like the sound of the V8 then get the V8. If you like the sound of a V8 but want a stick shift find a car with those features.
Those prices seem high to me. The best way to find out what competitive prices are is to go to ebay, find cars of the year you are interested in, and look at those that sold (completed listings). That will give you a good price range estimate. Coupes tend to bring the lowest prices and fastbacks tend to bring the highest prices. Convertibles tend to be priced less than the fastbacks and more than the coupes.
If a car has a six cylinder engine that will reduce the value further.