For just a private citizen, not to be used for a business. Is that even possible?

It technically needs to be for a business.  You need to own your house unless your leaser is willing to alow you to be a firearms dealer on their property.  Need a safe or 10.  The fee's have been raised under the Klinton admin. to prevent you from doing exatly what you are thinking about.  You need to buy a shitload of firearms to make it cheaper for you to amass your collection to offset the FFL fee.

Ohh I see you are in Maryland.  Shit who knows there.  All my pistol cases say "Not for sale in Marryland"  so I assume it's not as easy there.

its not worth the hassel if you just want to further your collection

In Peoples Republik of MD, pistols must now have an integral safety lock if they were made after a certain date, and they also must come with a fired shell casing. The result of about 20 plus years of Demokrat rule. :-(