We have a couple suppliers to pick from, but typically all the business goes to one unless the other is significantly cheaper.  I dont't really care for the games anymore and will only tell them the other guy beat them and better luck next time.  On occasion I have discussed with the fuel the price of on-highway diesel and how does the one station in town sit 20-30c/gal cheaper than the others at time.  A lot has to deal with their contracts and when they buy fuel.

Edit to add:
I hate it when suppliers ask where they need to be on price.  Some take offence when I tell them as close to zero as possible and say they can't give it away.  I am not asking them to give it away, rather give me your best price and don't get pissed off if you don't get the business.