As far as know all vector apps do text on a curve easily, which means Adobe Illustrator, CorelDraw, Xara Xtreme, Serif DrawPlus and probably Inkscape (though I don't use Inkscape, so I don't know if it can for sure, but probably though), the last one being free like GIMP. Every vector app I've ever owned, and I owned three of five of those listed above do that no problem.

The basic version of Xara Xtreme is only $49 (I use the Pro version though which is $249) does this and anything else you need very easily. Not that I'm especially recommending it over the others, but if you're familiar with any of my maps, all of them were created or otherwise composited in Xara Xtreme.

Go download Inkscape for Free and try it for text on a curve, it probably best fits your budget!

GP