Three separate trips means a third the number of buses to service the same number of people (assuming equal distribution). And a third the number of drivers/etc.
My best new car buying experience was using the methods described in the book "Car Buyer's and Leaser's Negotiating Bible" by William Bragg. The book is out of print but basically consisted of faxing/emailing dealerships within a 300-mile radius and asking for a quote on your chosen vehicle. Then, after getting the lowest quote, inform the higher dealerships and they almost always go lower. Repeat as needed.
Personally I play a bit on my phone using the Droiddippy app. However you can also play via web at http://droidippy.oort.se/web.