Talk is cheap. Even w/ a contract, what happens if you don’t hit the volume you say? Do they have to be jerks and take you to court? Are you going to cut a check for the difference? Just saying you’ll use them exclusively means nothing. Exclusivity on zero is still zero.
You really have to SHOW them you’re a serious player in order to ask for a really competitive price. Why should I, being the printer, take a financial risk on you? The odds are actually better letting you go to my competition and let them take the risk.
Also, don’t think that the shop that comes in the least is going to be the best deal. What happens if you do lock into a long term agreement and their work starts to suck? I pay my printer extremely well! It’s an integral part of my business. I rather pay my guy more and have the luxury of being one of their most profitable clients. This way when I need something done, it get done ASAP! How much is that worth?
Take it to the total extreme. You love your print shop! They charge you the best price you know. Always run your small orders whenever you want. You have no screening or set-up costs. Doesn’t matter if you print one color or 10, it’s the same cost. Now you’re wondering why the shop went out of business and you’re back to square one… only worse!