Tripod3, most of your comments are totally wrong. Paper records (4473's) are only required to be kept 20 years (may seem like forever) but every so often, I have a burning party and properly dispose of all 4473's over 20 years old. According to BATF, when going out of business only the "Bound Book" is sent to a special address and it can be sent by any carrier (USPS or UPS, or whatever, can even be taken in personally.) Cost of a license is, as mentioned above, initially $200 for three years and after that $90 for 3 years (wait gotta look it up, may be for 4 years.)
As for dealer ordering a gun and buyer getting denied, the gun belongs to dealer and does not have to be destroyed, he can resell it. Money paid is between the guy who ordered it and the seller. There is nothing to require dealer to distroy gun unless it is declared "contraband" by the BATF (only contraband guns I have ever seen have been Title II and improperly regestered or built without tax payment). They do not charge for you to turn a gun over to them even if you or they wish it to be destroyed.
If FBI passes a NICS check on someone, they cannot later call and deny it. It is a done deal. If they make a mistake, you should assist in them recovering the firearm if you have delivered it and had customer sign the 4473. FBI cannot come into store or call and demand a records check without a court order, they CAN ask and you should help, but only BATF can require you to allow them to inspect records.
I have been an FFL for over 40 years and also Class III stamp holder.