If you were going to pay something in the $100 range I'd go for a known quantity like a
Mitutoyo they can be had on ebay for $145. If you wanted something in the $50 range I'd buy one from
M&G on ebay I've had good experiences with them in the past. I would guess most products less than $100 are made in the same factory so its a bit of a lucky dip as to wether you get your moneys worth.