Like the above people said, there is absolutely no reason to NOT use a wet kit if you're planning to try Nitrous - unless you fully plan on destroying your engine.
Either you have the money and it's a possibility, or you don't do it - plain and simple.
And in fact, a wet kit can be pretty cheap to set up if you go find suitable solenoids yourself, and buy the smaller custom made parts from a company like Nitrous Express (Just the bottle and nozzles). The cable can be acquired pretty cheap, and you will need to make the jets yourself anyways, because any commercial nitrous ones are like 5x the size you would need for an ~80cc displacement moped. There was an amazing site posted earlier that I can not remember the address of...it could be in the other thread about nitrous on here.
@ Hitace - you are going to destroy your engine; I promise you that. If it's not directly from leaning out, it's going to be from a combination of timing + leaning out. Even when you carefully select a jet that's optimized for nitrous, the timing gets advanced as you pump nitrous into it. You're going to blow your engine, it's just a matter of time.
Those $30 kits on eBay or whatever are just an accident waiting to happen.
Sure, you can spend $1000 on a premade wet kit - or you can make your own that's actually better because it's MADE for mopeds for like $2-300.