I was looking into this before I retired. For me it was too much BS.
FFL Licensing and record keeping
City Business license
Corporation Commission License
State Tax ID
Business Tax Filing
Set up LLC to protect personal assets.
Business bank account
One item that BATFE and I discussed and could not come to agreement. ITAR fees.
Supposed to be yearly fees for international trade. My argument was that I would not be doing any international trade and there was no need to pay the fees.
ITAR isn't needed with an 01, were you looking to apply for an 07?
Re costs.... I ran an office FFL in CT. Only did transfers as I never got a chance to get it going since I moved out of state soon after.
My total costs in CT were....
$150 ATF application fee for an 07
$120 to register for Sales and Use Tax number
$10 to register a DBA with the city it was located
$000 to register as a Sole Proprietor
So about $300. That was in a town that allowed me to bypass zoning. When I tried to do it at my mothers house in a different city the zoning fees were about $3,000. It was cheaper to rent a $200 a month office space at the time.
Another thing to consider is that if you stock ammo the fire marshal may require overhead sprinklers.
Good luck with it! I got to see tons of guns I wouldn't have seen ha it not been for the small transfer business I was running.