I don't have an AA card, but I'm pretty sure that...
1) The basic Citi or Barclay's AA card will cost $95 a year, get you 2x or 3x (I'm not sure) points on AA purchases and a free bag.
2) The Citi Executive card will get you Admiral's Club admission, but it's around $450 a year.
There is no low-fee card that will get you lounge access.