I picked up a Superchips Cortex 2950 for my SS (it's now an outdated model, but can still be found). Paid $288 back in February of '14. A lot of people hate Superchips, but it's served me very well. Clearly it's been good for the car too. My mpgs went up 1-2 on average running 8 cylinders full time on the 91 tune. Yes, up. My transmission is also much happier. My trans usually quits/needs major repair around 80-100k miles according to most experts, including Triple Edge. Still going strong.
But most importantly, no more burning a full quart of full synthetic every 750 miles and smoke pouring out of the exhaust pipes. After the tune and disabling AFM, there's absolutely zero oil usage. That alone has literally made it pay for itself. I've had it for 55k, ÷750 miles/qt = 73.3 quarts of oil saved, @~$5/qt =$366.50 saved.
The only thing that caught me off guard was the first mile of driving after tuning the trans. It was a bit scary, then became clearly better than stock. Obviously it had to relearn.
If you're interested, you may be able to find it cheaper, but they're currently ~$300 used on Amazon. It may not be the "best" option, but it sure beats living with AFM.