I can't imagine anyone who does not by now own a digital luggage scale, if not to avoid the unpleasant surprise of excess luggage charges, at least for curiousity. I have one of the Balanzza versions, works well, which we use prior to leaving home, but generally leave it at home as it's another 8 oz. to carry.

BUT, especially for those who know that they'll be shopping at their destination, Balanzza now is introducing a MINI version, just 3 oz., that would be easier to justify taking. Cost and other details not yet available, and not even a link on their site, but one other site at least gave the weight.

http://www.balanzza.com/

I used these scales often as my job requires alot of travel and found the battery life to be inadequate and was costing me almost as much as an excess baggage charge! after alot of searching around i managed to come by the ultimate digital luggage scale by www.globalbagtag.com and these claim to have a 2 year battery life! so far they have not let me down and seem to be pretty accurate i would recommend this to any frequent traveller.

The Mrs. and I use a common kitchen scale at home, one of those old spring kind with a large hand that goes around the dial. Its pretty accurate, within four or five ounces. The carry-on scale is a fishing scale that is spring powered also, has a hook, and a place for a couple fingers. It is also accurate to withing five ounces. That's enough for me. No batteries.

Funny, but several of the FISHING scales listed by Bass Pro Shops look an awful lot like luggage scales! For $22 they have one that weighs fish (or a suitcase full of fish) up to 110 lbs., has two LED's to serve as a flashlight, includes a 36-inch tape and a thermometer to boot!

The one I have is a Zebco, about 40 years old, weighs up to 32 pounds, measures up to 31 inches, and MADE IN AMERICA!

I purchased a mechanical luggage scale ( Travelon)
from TJ Max for $5.50 ; today. Compact and convenient.

How about taking your bag down to the post office and weighing it on their package scale? It is free. At that point you will know exactly what the bag weighs and you can plan for souveniers.

"How about taking your bag down to the post office and weighing it on their package scale? It is free."

Free...but NOT convenient! There just is not substitute to having your OWN luggage scale, to weight a full bag, or items that weigh at least five pounds or so. The current Balanzaa is about $25, and on some websites, actually FREE if you're buying certain bags. However, I'd think that the newer and even smaller version would be preferable, particularly if a traveler expects to purchase items at their destination.

Beyond that, having a really accurate digital scale to measure items up to five pounds allows one to assess choices in clothing and other gear, particularly when airline weight limits are an issue, not to mention that other weight limit...your own shoulder. I have a Salter, meant for kitchen use, works well in either metric or English measure. I even use it to measure....gasp, FOOD!

The Balanzza Mini I now see listed in my current L.L. Bean holiday circular, for $22.95, and again, I recommend it.

Of course, for any domestic travel, the carry-on only traveler doesn't really need one, save of course for curiosity, but if one's travel partner is a check-in type, it can be a useful item to have, particularly prior to one's return, to avoid unpleasant surprises when a bag exceeds 50 lbs., or on some airlines, less than that.

I have the Mini, it was an upgrade from the unwieldy, non-digital scale I used before (which was never correct).
The only downside to this one, when I'm not using it during my travels (and when it lays unused at home), I have to take the batteries out. The on/off switch activates any time something presses against it accidentally, packed in a bag means this can happen anytime and drains the batteries very quickly. I like it a lot though, excellent little scale.

My Balannza Mini, in the REI-branded version, as ever proved very handy in dealing with not my luggage so much as my wife's full-sized bag, especially as we returned a few nights ago, via Israel's Ben Gurion Airport. After my wife underwent a merchandise check for a VAT refund, she put some Ahava cosmetics including bags of Dead Sea mud (yes, real MUD) into her large case. As I hefted it I recognized that it likely had gone over 50 lbs., rapidly confirmed while still in one of the lines by use of the Mini, allowing use to transfer those items into my much lighter carry-on roller bag.

Unfortunately, the battery cover of the Mini popped off just as I completed the weighing. I could not find it, but realized that REI would replace the unit at no charge, so I relaxed.

Once home, my wife opened her bag and began to bemoan that someone at Ben Gurion had "stolen" all of her Ahava cosmetics...until I pointed out that they were in MY bag!

Doing a final clean-out of my TB Co-Pilot I did find the little cover, but for future use, will put a strip of masking tape over it and will travel with an extra CR2032 cell (which are actually cheap if you buy a strip of ten via the internet.) These cells fit a number of items, including the Kestrel electronic wind gauge with thermometer, hygrometer, barometer and altimeter that I used several times....mainly to confirm elevations BELOW sea level!

I have the Balanzza mini as well.
The lid popped off mine and no longer clicks into place so I now hold it down with a rubber band. When I'm not using the scales I remove the batteries, the one down-side to this model, it turns on too easily if another packed item squashes against it, then the batteries drain rapidly.
I take mine on trips abroad, some European airlines are so strict with carry-on weight and I really don't want to pay their fees or have my bag checked. (That is why I always take my Adventure Jacket........extra packing space without being questioned or weighed).
I can always count on myself shopping at some point on my holidays.