I charge:
$15 per long gun.
$20 per used handgun
New handguns are an additional $15 each because I have to make a 3 hour round trip to provide a casing to NYSP. If the casing comes with the pistol, which some still do not, I have to mail it certified mail to CoBis.
I'm required to provide a lock with each gun, and NYs lock law is written in such a way that many of the cheaper locks that used to meet laxer gun lock laws wont pass muster here. I'm not going to eat the cost of that lock.
Its still mainly a hobby for me, and I charge what I see are minimal fees to recoup my costs. There are no brick and mortar gun stores in my area anymore, and very few of us tabletop dealers left to boot. I would like to have been able to open a store when I retired from my other jobs, but now I'm of the mind that I'll be leaving NY when that happens.
As for the OPs claim that he does all the work, I've had plenty of customers over the years who wanted a particular gun, didn't have a source in mind, and had me calling all over the country looking for the cheapest possible distributor for their desired product, to the point that the customer would quibble over an extra $5 in shipping cost. So please, son't tell me that you do all the work and the FFL is doing nothing.