Quoted: I would like to hear as well. I am seriously thinking about applying for one myself her in the near future. I keep hearing without a storefont its impossible?

It is possible without a storefront.  It really depends on your local zoning laws.

It helps to have a state sales tax ID and a EIN as this demonstrates that you intend to engage in business.  You will need a location that is not zoned or that allows a commercial use.  A personal home is fine as long as it is not restricted in any way - they will check.  You will need secure storage (i.e. a safe) and an alarm system.  You will need at least some business hours - they don't really like the "by appointment only" setup anymore.  A few hours per week is fine.

You must intend to "be in the business".  You cannot get the license just for expanding your own collection.  When they do their annual inspection they will want to see that you are transferring guns to people other than yourself.

Remember that you give up some 4th Amendment rights and other rights related to searches and seizure.

I can tell you that in general the markup on guns is very slim - usually around 10% at most.  So careful consideration is in order.