I've had the N/A and the base. They're both fun, but different. For starters, the Base I had was nearly impossible to drive on wet pavement in my area due to the weight of the car, torque and lack of traction control. It could be done, but it took work.
My first solstice I think I stole. she had about 100k on the odometer. Everything was mint, and someone went through the trouble of adding a wonderful aftermarket bluetooth system with great sound and red LEDS to match the interior lights, Fujita F5 CIA, cat delete, custom exhaust, upgraded the injectors, and even put a tune in it. EVERYTHING else was stock and more or less mint! It had been traded in at a used dealership, and the dealer had no idea what it really was and even tried to tell me it was a V6.... (I'm guessing he didn't even google it) He had a very pretty price tag on it. $3,500. I talked him down to $3,000. This price is not typical. I've since seen them pretty trashed for more money.... please go over the car carefully before purchase.
A GXP on the other hand... well, for the most part, I'm seeing them sell for between $12,000 and $15,000 in fair to good shape. I gave $15,000 for mine.
I recommend looking at small dealers and REPUTABLE online market places for better prices. ONLY pay in person, and only after you've driven the car. If it's too far away to go drive it, then it's probably not a good idea. A lot of scammers and shammers out there. INSPECT THE CAR! Look on REAL Pontiac Solstice/Saturn Sky Owners, on facebook for an inspection guide that will help you see what you need to check.
Wraps can be a wide price range. I've seen reports of these cars running from as low as $2,500 up to over $8,500. Keep in mind, wraps will protect the paint that is there, BUT the car will have to have a nearly perfect paint job for a wrap to be applied, else when the wrap is applied it will show, bubble, and/or break the wrap. If your not concerned with the paint, then "bondo" or paint or another product can be used to correct paint chips, but keep in mind that wraps don't last long, especially if you're going to be storing your car outside. Best case scenario, you'll get a few years out a wrap. Worst case it could fade in less than a year.
I have seen a solstice base with over 200,000 and it was still running just fine!
Not a lot of differences between the years except for the coupe version... there are essentially only 2 trims, the base and the GXP. There are several options, stock radios, seats, interior and top colors, "power" seat (it only lifts the seat), and other things to look for, but anything can be changed for a fee.
I would recommend finding something you like in your price range that is in proper working order. Obviously find the best deal and condition you can for the price. Then, if it's not enough power, you can always add and modify as you get the cash. Join communities like this and ask questions. You can even ask if anyone has a part you may want or need. You'd be surprised how many parts are on here!
As for mechanics, first... try to learn a little on your own. It will save you an exceptional amount of money! HOWEVER, if you decide not to try, then I recommend asking around in your area. Car clubs and vintage auto drivers can normally help you find someone who will be respectful to you and your ride.
Good luck in your endeavor, and if can help in anyway, please let me know.