Once you start modding the car you are not going to even get close to the value of the mods back when you sell it, so an un-modded car will generally not be much cheaper. We are talking generally here and there are exceptions, it really just comes down to what someone is prepared to pay for the car.
If you try to do the import yourself it is really complicated but if you go to one of the importers just tell them what you want and they will source you the closest car to your requirements. Personally with the exchange rate the way it is at the moment an import would be fairly expensive.
I'm with you as far as buying unmodded so if you do chose to go down that path you can choose what you want done yourself (reason I bought an unmodded GTR V-spec). The only disadvantage of this is the cost, I've spent upwards of $10 grand in my head already (exhaust, turbos, ECU, suspension, oil cooler) and I haven't even thought about engine internals yet.
From what I have seen you will have a bit of trouble finding an unmodded car so maybe an importer would be the way to go. Hth