If you plan on doing more than just basic bolt on stuff, look into what your local tune shops use for their tuning....or go with a wideband data logging system so you can mail order tunes as you go...but thats gonna cost around $600-800 for that setup.
You can go on ebay or check out the classifieds for used sct or diablo tuners. MAKE SURE THEY ARE UNLOCKED and have it in writing that they are! If someone says they can hold tunes for up to 3 cars...they are bullshitting their ass off. When it says it can hold 3 tunes...it means it can hold 3 tunes for a single car. If you do buy a locked device, buy it for less than $100 then send it into SCT to get unlocked for $150
HMUSM and Trick Tuners are always on the forums and sell a great tuner setup for around $380 or so. They are great people to deal with...really should have bought mine from them, but was in a hurry and local crappy shop said they could get it in next day....ended up with a product i didnt really care for.
If you want to do your own tuning--which isn't rocket science, but does mean you need to have a clear understanding of how engines and engine control systems work--then the Sniper Special Forces package is a great place to start.
The Sniper SF allows much more control of things than any handheld and let's you tune two cars with the basic package, and as many as you like by buying additional "bullets" for $150 each (tune up your friend's cars). Here are some screen shots:
It also offers auto trans control for shift firmness and shift point modification by RPM or MPH. Their support is top-notch, and the user forum is active and well-supported as well.