you can get a GT500 for $50,000, but the unoptioned $30,000 2011 GT performs similarly to the GT500. However, I've never seen a GT sell for $30,000 as they all get optioned and end up closer to $40,000. The one I priced to my liking was closer to $43,000. At that point, just spend the extra $8,000 and get the GT500
Since you can order the GT500 from any Ford dealer and website and don't have to deal with Shelby Cars of America directly, I consider it a basic kind. Yet, I don't consider the Roush's and Saleen's "basic" for these comparisons since you have to go to a Roush or Saleen certified dealer.
I haven't looked at the numbers comparing the Camaro SS to the Mustang GT, but when you are, make sure you are comparing the 2011 5.0 instead of the 2010 and older 4.6.