These would not be too hard to make, if you have a sewing machine. They don't work for me, since I sometimes need the bathroom urinal, but, my long muscle tee's are about a close as you can get, without the snaps. I'd just modify one of those (or a dozen...), if I really needed them, and dye them with solid colors & assorted tie-dye.
Honestly, you just have to be slightly smarter than the average bear to come up with stuff yourself, and save a bundle! NO, maybe not as babyish as some want, but definitely half the way there, for a fraction of the price!