Hi,

There's plenty of vendors out there who sell sub hulls, I'm not an expert on each but I can tell you that a starter sub shouldn't be too small nor too big, it should be easy to assemble, not too complicated to operate. A lot of subs can fit under this catergory, Try the SubCommittee Vendors Link page, there's plenty of links there.

Large model of the Typhoon for under 50 bux? It's PRETTY RARE to find something of that price on the market, look at it this way, a small kit of the Typhoon at 1/350th scale costs about from $30-$40, the size is about around 19 inches. If you want to aim for something bigger, the price bar is pretty high, from the kits I've seen, I didn't find any that were under $100[]

I don't really have PVC experience, I'm sure that a lot of guys out there will answer this question better.