First, make sure your state allows them, then be prepared for sticker shock. Suppressors are spendy and they are definitely NOT Hollywood quiet.

The $200 tax stamp goes to the BATF/NFA branch when you fill out the paperwork for the transfer after you "buy" the suppressor. The suppressor will remain at the dealer where you bought it until the stamp comes back, which can take from 4-12 weeks, sometimes longer depending on back log.

Suppressors are anywhere from $500-1100 and for the most part, the old saying "you get what you pay for" comes into play. Silencer Talk is a great place to start your research.

Good luck, but keep in mind, once you start going Title II, it'll become the most expensive habit you've ever had as you will want more (sbr's, FA, more suppressors)

Stay safe.

zhurdan hit the nail on the head.

You might want to look into suppressing .22lr. A little less money and more fun (quieter than center fire). I would not go the cheapest route either, because that $200 stamp is only applied to that suppressor (can not be transferred to another). Also, if you do get one, make sure it is serviceable (one that can be taken apart, not welded closed) so it can be cleaned. I look at it as a one time investment and want it to last.

Can we presume you are interested in a sound suppressor and not a flash suppressor?

You need no special license for a flash suppressor.

You need a threaded barrel to accept the thing.

If you do buy a sound suppressor be prepared for a lot of questions if a cop sees it. If you are buying it so that you won't have to wear hearing protection, then everyone at the range will need one too.