i started with gimp, went with it for 2 years then switched to photoshop, and realized gimp REALLY limits the kind of art you can do
Photoshop DOES cost money(unless you get it at the right place:P)
The nice thing is, if you stick with gimp for a long time, and ever decide to get photoshop, it will be nice and easy (they're both just as complicated, btw:P)