Stub Hub, Razorgator and the NFL Ticket exchange all work very similar, they control credit card data from the transaction and will back charge you if the tickets that are delivered turn out to be bad.
E-bay has some safeguards, but they all involve a hassle and will leave you out your money until they decide to refund it.
The riskiest tickets are bought from Craigs List and street vendors as the minute you loose control of your cash, you have almost zero ability to recover your money if something goes wrong.
If you are forced to use CL or street level vendors, meet them at the box office or ticket gate and don't pay until the ticket you have in your possession can be verified good.
My advise to anyone traveling from far away that needs tickets, use one of the named broker companies listed earlier and just deal with it as overall it is not most likely that much of your total travel costs and taking the risk just is not worth it.
Concerning ticket availability, the deal can be brokered and done anytime, but the NFL teams don't release tickets until late July or early August and most probably use the automated e-mail systems for delivering tickets that you just print out a day or two before the game.
For those that choose to attend the temple "QWEST" bring your best and be LOUD.
The opposition has no hope!!