Bore gauge

So I am thinking of buying a bore gauge. I see on ebay a wide range of prices from 19.99 to 299. I am planning on building a lot of engines.

So i am really wondering if more expensive means more accurate or more brand name.

Proform from summit runs $109. And looks like a great unit.

They also have this comp cams unit. Do you guys think it's better quality or more brand name??
COMP Cams Dial Bore Gauge Combos 5605