If your looking for accuracy no better than 10/100's I would go with a postal scale from walmart and digital calipers from a tool store that seem to have them on sale a lot (harbor ?)
I bought a set of digital calipers from Harbor Freight CHEAP and wanted the plastic movable/measuring teeth (two) instead of the harder stainless steel calipers which will probably last longer. The ones I got you can ZERO the reader when you close it and I just didn't want to have the steel teeth scraping up my cue. When I apply a taper, I might meaure each inche of the shaft dozens of times. A pair of stainless steel teeth instead of plastic could scrape up a wood shaft in a hurry at least when you have caveman hands.
Bring shaft to post office to weigh. It's free and always accurate.
JoeyA
i was gonna post that same thread link as shamadam so it looks like he's got you covered on a caliper. #30 looks like the best deal. has metric and goes into 2 decimal places or more. as far as scales, don't even bother wasting your money. just go to any post office.
Or, if you're fortunate enough to live in a state where bars/taverns/clubs can sell pulltabs, most bars/taverns/clubs now have pretty accurate electronic scales to weigh their pulltab bowls. These are way more than accurate enough to weigh pool cues.
I have an old tip gague from Viking that has holes in increments of 1/2 mm that I use in addition to regular calipers. The gague works good when you're trying to determine the length of the taper of a shaft.