I would also be willing to help... there are a variety of overseas sources that could provide them. The cost of importing may require you to take more than the 900 you require but the cost could be substantially lower than .90.
You may contact me at firstname.lastname@example.org. This is not an advertisement as I do not do this for a living but I am willing to help any entrepreneur get started.
I looked at dollardays.com..notta, orientaltrading.com, notta but i just found.....http://www.discountmugs.com/usa/coffee-mugs-7102-b asic.htm . You can get imprinted for .67 cents - .71 cents with a small setup fee, it would run about .80 cents a cup with any imprint, healthy...logo etc. It has a 5-7 day turnaround. Hope this helps.