The only reason to avoid the dealers is to save money. It's a valid reason, but dealers bring a lot of other things to the table.
Safety
Security
Knowledge
...and you get to see it before you make any sort of commitment to it.
BATF cannot decide they "want to" look up any particular gun for giggles. A law enforcement agency has to request a trace from the BATF to search for the original purchaser. The only way this can happen is for the gun to be in possession of that law enforcement agency, or have the serial number of the gun (used in crime, stolen, etc.). If you don't use the gun in a crime or have it stolen then you'll never have to worry about a trace.Any firearm purchased through an FFL is entered into their bound book. If the BATF wanted to, they could trace that firearm to the original buyer. If I then buy that same gun from the that individual FTF there is no record of that transaction, and no easy way for Big Brother to know what I own.