I've gotten all mine (I have 5) except one from Silencer Shop. Other than an AAC 762-SDN I picked up from SGC when they were having a screaming sale ($850). My other issue with SGC is they charge $75 to do the transfer... I've never seen anyone with prices anywhere close to Silencer Shop and they typically have a bunch in stock.
You don't pay sales tax and they ship for free so I save enough money on each one to more than pay for the tax stamp.
Yes, they have to do a dealer to dealer transfer...but they e-File those and they don't take more that 3 to 4 weeks max. So I'll take and extra 4 weeks to save $200 to $300.
Silencer Shop should be able help you find a dealer locally that e-Files as well. They also have EXCELLENT customer service. You won't be disappointed if you use them.