[Rodney]

y question is, can i buy hanes shirts, or hyp ringer t's (for example), then take their tag off and put on my own....legally?

Yes, this happens all the time. Do a forum search for "relabel" and you'll find lots of information about it

i would imagine too, that buying wholesale would be best, but then how does one buy, say the hyp shirt, at wholesale.

I believe the hyp brand is sold wholesale by alphashirt.com. Here's their blank catalog:
http://www.4logoapparel.com/DF6162D...+Brands+%3E+HYP%AE+Sportswear+%3E+Mens&sc_id=

You would need an account with alphashirt.com to get them wholesale (although your screen printer probably already has an account and could get them wholesale for you so you don't have to worry about buying the shirts and getting them to the printer).