There seems to be quite a buzz about the net regarding long sleeve leotards. While I agree that they do look better for presentation purposes, I am not sure how practical they are. Especially if you live in a climate that gets hot during the summer. It is for this reason that you only see a limited number of these gymnastics leotards, with the majority of sightings occurring during meets (in the southwest anyway). However, for those athletes living in cooler climates, these outfits may actually be beneficial.
At any rate, I have managed to find a couple of sites that carry these long sleeve leotards. One of the sites to keep these on hand is look-it.com. I have spent some time on their site before, and they seem to have a fairly wide selection. Additionally, they have told me they pride themselves on their low prices on girls gymnastics leotards.
Another site that peddles in similar gymnastics apparel items is Danskin.com. Keep in mind that Danskin deals not only in gymnastics apparel, but they also focus on leotards for dance and ballet as well. They have a wide range of leotards and gymnastics related items, so you should be able to find what you are looking for. Be forewarned that they are not the least expensive manufacturer. However, my experience has shown that their leotards are high quality and will last for a while.
Now get out there and stick it.
Gymnastics Leotards