I haven't tried in a long time. I used to make my bathing suits when I was a teenager (and had more courage). I just remember that spandex is very slippery. I used some of that double sided seam tape to keep the seams in place while I sewed. It helped a lot!
Other than that, I made my son a pair of swim trunks a couple of weeks ago.
http://www.flickr.com/photos/tawnybee/3518683561/in/set-72157617867262021/I didn't have a pattern, but I just made regular shorts and made the lining pattern a bit smaller with elastic around the legs and sewed it all together. Turned out great!
I think you should be fine making a swim suit. It'll cost half the price (even less) and you'll have a one of a kind outfit!
