"Hold the highest" would be nice IF you slowly, gradually, raise the luggage from the floor without hitting anything on the way up. Otherwise, you will get a falsely high reading.
Without "Capture and hold", it can be tricky by yourself to weigh 50-60-70 pound bags. It's easy with two people for one person to look from the side as the bags hang from the scale.
I'm thinking "$50" was a typo by Greg. These things only cost $30-50 at the Hudson News at the airport. On eBay, they are $3 including shipping. Here's the kind I got four of (for me, and gifts for frequent flyer friends):
http://www.ebay.com/itm/20g-40Kg-Pocket-Digital-Scale-Electronic-Hanging-Luggage-Balance-Weight-/310708286003?pt=US_Pocket_Digital_Scales&hash=item4857a83233
$2.77 including shipping. Takes two AAA, not included.
Weighs to 50 pounds (in pounds, kg or jin), starting at 0.02kg / 0.04 pounds and thereafter in 0.01 kg (10 grams) / 0.02 pounds increments. I'd never had a disagreement with airline scales so at 50 pounds it is within half a pound, my sense is that it is closer than that. I hadn't checked the low end until just now, but I weighed a pound of butter package at 1.08. Then I tared it with the empty cardboard box and got 1.04 for the butter and wax paper around each cube. Assuming the Amalgamated Diaries of Wisconsin doesn't put in any more butter than required (I'm pretty sure about that), it appears to be within 0.01-0.02 pounds (i.e an error < 1-2%).
Definitely not for selling pot much less cocaine (at street-level quantities), or tweaking your soda-can alky stove, but for checking fuel canister levels, etc, it seems adequate. Great for luggage and food drops and postal parcels. For stuff that doesn't hang easily, just tare it with a plastic grocery-store bag hanging from the hook. Pro tip: at home or on the road, hang it from a closet rod for easy, eye-level use.
I take about 80 flights a year, so I actually don't use it myself. Once we moved to Alaska, I calibrated my arm for 70 pounds by hefting and weighing many bags. Then, post 9/11 and the 50-pound limits, I recalibrated my arm. I can pack a bag to 49 +/- 2 pounds and then I leave a book or some 1-2 pound object near the top in case I need to shift something to another bag.
