Which of those 3 suppliers is closest to your shop? Do you have any experience with the tech support or customer service of any of them?
for equipment, always try to go with the company you feel will be able to service the machine the best, if it breaks down, you will lose far more money than you saved if you have to wait 2 weeks for a tech to come out.
having said that, I would imagine whatever shop you choose would be able to "price match" the lowest bid if the $ is close like you said, they are not going to loose a sale over a small amount of $ (I would think)