Getting your SOT is easy, simply get a FEIN number, fill out the app and send the NFA branch a check for $500. You will be able to then own and sell AOW's MG's(for sale outside the state or to other SOT's) and SBR's. You will not be able to possess suppressors though as the law states you must either be an ammunition manufacturer or firearms manufacturer. And even though SBR's are ok I have heard that the NFA denied a SOT transfer request. Not sure of the final outcome though.
It seems that even the price of post sample weapons has gone through the roof just like transferable and pre samples. I paid $1395 for a MP5 in 2003 and recently saw them selling for up to $7700 on Gun Broker! My $500 Uzi post sample is in the $3,000 range. Oh and if you figure the cost of feeding them the MP5 will run about $185-$215 a minute to shoot!
ETA: The license runs from July1 2015 to June 30th. So if you pay at the end of August you lose one month of your license, no pro rating.