Popping this one up from a month ago. I didn't see it when it was originally posted.
To get a great deal on BM paints, you'll have to get the contractor's discount. This will drop 10 - 25% off the price of the material. Also, their Super Spec paint is quite good and runs about 30% less than the Royal label. Finally, if you are interested in doing a great paint job, ensure that you get some primer tinted near the color of the paint you are going to be using. Primer is way cheaper than the paint will be. The primer at Benjamin Moore is not cheap. In some cases, it might cost more than a gallon of paint. Head to Lowes and get 5-gallons of PVA primer for $30 or so. Best of luck!