Jenn has had some luck with Milanoo, however that is all they have bought from there is zentais. They have had to do some serious surgery to make them fit them properly.
Kwik sew has a couple of patterns you can alter into what you need if you are willing to try it. Sewing spandex is a lot easier then you think! Plus you get full control over how weak or strong the spandex is. [link]
Wow, great work. Oh, so they didn't come fit to their likings? Thanks for the inspiring words, I definitely want to try my hand at it now, I believe I'm of a similar mind, so I'm not going to be happy with it unless it fits right :0)
They're not exactly made with a lot of care and effort. The zentai suits from milanoo may need a lot of work to fit right, but they're still worth it in that what you pay for them is often much cheaper than what you would pay for all the fabric you'd need to make it yourself. You also don't need to fuss with making the fingers of the attached gloves, for example.
But making it yourself is a huge learning experience that cannot be replaced, too