You can drop Gold on him as long as the vendor belongs to that specific character you are on. You need to drop gold coins (Cannot be in bank check form), must be stacked gold coins. Kindof a pain- but you can do 60,000 gold stacks at a time.
OR
A much faster route is to place a 1,000,000 (For example) gold check on your vendor and then set the price for 1,000,000 gold as well. Get on an alternate character and buy the 1,000,000 gold check. That is the quickest way of placing bulk gold on your vendor.
