You could get a lease in the cheapest Commercial/Industrial office space you can find. A small 500 sq/ft. lease in one of those sheetmetal style light industrial/office rows could be pretty affordable. The overhead would dictate that you do more business to cover expenses of course, but even if it's not a "showroom", you could fill it with sufficient gunsafes/security to operate on a "by appointment basis", and act as an FFL who focuses on transfers, and custom "gunfinding" etc. for his clients. Business hours/availible appointments could be 5-9 pm and weekends only. You'd figgure that people with jobs to afford guns are busy and couldn't come into your store outside that time anyway.
If you incorporate, and you can't make a go of it, the corporation is liable for the expenses, not your own finance/home/assets so if you can secure capital in the name of the business, failure shouldn't affect your personal life too much other than the time and effort invested. And then you know you at least tried in persuing your "FFL dream".
Advertise yourself aggressively with business cards at gunshows to passers by, on the internet on various gun-boards buy/sell forums, and while attending pro-gun functions, or hanging out at the range. An aggressive no "transfer focused" FFL who catered to the new breed of internet/auction/Shotgun News savvy buyer could find a niche.
I think it might be a way that I'd try to start out, were I looking to become an 01 FFL. If I made a go of it enough to open a real store, I might just keep the original office open for transfer/low margin work so I didn't have to parade the "good deals" in front of the less savvy buyers.