Forget limit sngs, NL sngs are where the money is at. SNGs (particuarly at party poker) aren't really about playing traditional hold'em (postflop). It's all about preflop. If you get a few key concepts down and apply them effectively, profiting off the lower buyins is extremely easy. I used to SNG quite a bit (700 at the $33s with 10% ROI, 1200 at the $22s with 29% ROI, 250 at the $55s with 17% ROI). This was mostly 6tabling.

Now I play O8 3/6 and HU sngs (I like them). At my current O8 skill level I'd make more off sngs ($80+ US an hour), but I just don't enjoy them anymore. Cash games are a nice change of pace. That said, sngs can be VERY profitable and there is a wealth of info out there about how to beat them. Try 2+2 forums.