Back in the 1980's and 1990's... Charlie Ro offered a nice volume purchase discount which was calculated at the end of the year. Don't quote me on the threshold ('cause it was adjusted somewhat each year), but I vaguely recall it was in the $5,000 area and then bumped up to $7,500... which if you exceeded, you received a 5%-10% store credit the following year based on your annual spend. For example, if you spent $8,000 in one calendar year, you'd submit all your yellow store receipts and receive $800 in store credit to spend the following calendar year. Sweet!!! 
I managed to hit the threshold one year, and I remember getting a Lionel GG1 Congressional Passenger set with the store credit. Today, hitting a $5,000 threshold is a no-brainer with prices being what they are now. So even if a volume purchase plan were offered now (which it's not -- at least not published publicly 
), the volume purchase threshold these days would likely be north of $20K. 
David
