If you buy it from out of state (pretty much any Internet retailer or manufacturer) you will have to have it transferred to a SOT in your state on a form 3, and only after that is approved (usually 3-4 months) can you start the form 4 transfer process (which can take between 9-15 months depending on where you're getting your timing info).
If you can find a local dealer in your state who has the can in stock, you can imediately start the form 4 transfer, which shortens your wait significantly. Failing that, I would try to find some of the smaller (but well thought of) dealers on the internet and buy from them. I have had a lot of luck doing that and have always come out with a much better deal on the can than I would have gotten if I bought it from a large retailer.
From what I understand, a FFL without a SOT can receive a NFA weapon, but only on a tax paid basis, which means they have to pay a $200 transfer tax AND wait the full amount of time for a form 4 transfer to the FFL before you start your form 4 transfer. That would mean you're looking at a timeframe of 18-30 months from purchase date to when you can take possession of the can and double the transfer cost if you use a FFL without a SOT.
Unless you're ok with that kind of wait, which is extreme even by NFA standards, you need to find a SOT in your state to handle the transfer. Even if he's an hour or more away, it would be worth it. You really only have to see him twice, once when getting your form 4 ready (SN/manufacturer/SOT info), and once quite a few months later to pick up your can.
