I found out the problem : When I was on the test server, I did a couple tests.

My First Test - I got the money built up doing the objective and I typed "tome2". Server acknowledged that I had the money for 2 tomes and bought them, but I gain no XP (as planned due to XP farming in the morning)

My Second Test - I got the money built up to 16k again, and this time "tome5". Server acknowledged that I had the money for the alotted tomes and spent all my money, leaving me $3500, but I gain no XP (because I'm still alone).

My Third Test - I brought a friend into the server, and we farmed 16k in a few rounds. I then typed "tome5" and then the server only gave me one tome.

Hope this helps ZERO.