You'll notice that some online sellers (Bud's, Guns.com etc) have a pretty substantial list of MD FFLs that are already known to them and have said they're willing to receive such shipments essentially out of the blue, because the seller will provide all of your contact info, and the local FFL can get hold of you once they've got the shipment in hand. Did one of these recently through United in Rockville, and it was a totally zero-fuss well oiled machine of a process.
Don't forget the md roster game! Is it on the roster?
Working with the FFL goes a long ways to making it smooth.
Also, may want to give them a chance to get said item in first if it is a new off the shelf item. Getting a "deal" to save $20 isn't a "deal" after the transfer few. They may be able to get the std capacity magazines as an FFL, all sorts of little nuances to address. Also, if you order it in and have an issue it is YOUR issue.
Factor in the transfer cost and all the extra MD bs before buying, for a handgun in particular the savings is usually non existent.
I second the roster check. I have a friend that has a gun in limbo. It is at the MD FFL, that model is NOT on the roster and the FFL rightfully will not do the transfer. The model number is different from the model number on the roster. The out of state seller will not accept returns.
Sometimes it's not about the thirty or forty bucks one way or another, it's about availability. My preferred LGS won't act as an inbound transfer agent for something they normally sell. For better or worse, that includes items that they sell BUT NOBODY CAN GET (because the supply chain is totally cleaned out), including them. But since I found a dealer that had the normally easy to find, but currently hen's teeth and no inventory coming any time soon from the factory pistol I wanted, I bypassed the LGS and bought remotely. Not my normal way of being.
But, now I'll have that .45 at least several months sooner than I otherwise would.