It depends on what variety you get on how weedy it is, and the flavor changes with each. Wild mint is very weedy, the mountain minst don't spread as aggresively, and I like the taste of them better.
You can order seed from prairiemoon.com
Wild Mint is Mentha arvensis
The mountain mints are Pycnanthemum pilosum, Pycnanthemum tenuifolium, Pycnanthemum virginianum, and Pycnanthemum virginianum var. something don't remember what. Prairie moon has decent prices on seed. $2 a pack and a good amount, 100-1000 per pack depending on seed size.