*rolls up sleeves*
I use Mitutoyo calipers, and find them to be a decent compromise between high quality and reasonably cost. I buy my calipers via use-enco.com since they often offer the lowest prices possible. BUT, if you want the best price, you're going to need to do some legwork.
I have the 500-196-20 for personal use.
Product LINK Currently, it's $94 via Enco. The way to get to the $94 price is through their "hot deals" catalog.
Catalog link Sometimes Enco offers free shipping, but that also requires some googling.
MSC might offer the calipers for a decent price as well, but you'd have to go through their sales flyers to check (sorry, I don't have time to do it for you right now, I found it in via Enco b/c I knew where to look). Currently it's $141 in MSC's catalog, but if they have another 35% off sale anytime soon, it'll drop to below $100.
I picked up my Mitutoyo digitals for ~$85 about two years ago. Sometimes the independently certified/calibrated version is cheaper than the "regular" version, but that's somewhat unusual.
There are other brands available for approximately the same price, but I again strongly suggest checking Enco's "Hot Deals" catalog to see what's on sale.
Edit: SPI calipers are pretty affordable these days, especially their anniversary edition, but I don't know if their reputations or products are trustworthy.
Checking MSC's sales flyers, the aforementioned
Mitutoyos are $95 via ther MRO flyer and their "Mitutoyo sales flyer." Use code
MACH10W to get free shipping until 1/16/09.
Well, that's my opinion. Cheaper calipers will still work, but I have never had to question the reliability of Mitutoyos.