Don't bother until you physically have the FFL in hand. You need it to get established.
There are a number of them who are ok to deal with if you are a small fish like I am in this big sea we have chosen to be a part of. The requirements are not great for some, some require minimum purchases and bank references. Pretty much all of them can be referenced through the web. I'll give you the names of those I have accounts with so you can Google their web addreses and contact information. Once you have all of the paperwork you need, FFL and business license/sales tax license, you can actually establish accounts with them. It is easy with these ones to either set up ACH debit accounts, check fax accounts, or deal with COD (it costs on the average of $13/shipment to do COD so that increases the cost of the sale. Not good from a business end unless unavoidable). A few of them upcharge for using a credit/debit card for purchases, most do not. You'll have to sort through the bunch and see what each one requires and offers.
Williams Shooting Supply
South Ohio Gun
Each one has their own policies and each has different wholesale pricing, as you will find out. My advice is to establish with as many as possible especially because inventory is so iffy. You'd be surprised as to how many guns are out of stock when you need to be available. Happens way too often. That's another story, though.