http://cobraplant.com/index.php

Lowes also carries a limited selection.

I got some of mine from an Ebay seller, Wellspring or something like that. They were listed as starts so I expected small plants. I got them in 2007 and they are huge mature monsters now. They seem to grow very fast so don't be too worried about getting little plants.

petflytrap.com

predatoryplants.com

or ebay are all wonderful options.

I've done everything from buying potted plants, to bare root, to root ball, to seed. i recommend both of the specific links if you are seeking pre-potted, thriving plants that will recover quite quickly. the prices for anything there are far from terrible and will be worth it for the trial.

ebay offers essentially anything you could ask for, ever.
no question.

just a matter of knowing what to search for. i've gotten into purchasing far more than just CPs from there, every time i have no trouble.

so quickly analyze what you're willing to put into these, as far as time, effort, resources. then, look into what plants match your willingness. i have too much time on my hands, and therefore am growing D.Spat, P.Moc, S;purple, white, and yellow (cant remember their specific names), B.Lini, along with several other non-CPs, mostly fruiting tropicals. and i live in southern ohio (horrid weather and only zone5, i think).

so it's all up to you.

try live ones first, make sure you know how to care for them, the basic rules for any one of them apply to all of them. then, attempt seedings if you wish. this website helps TONS.

overall, just don't overdo yourself at first.