I don't know any way around the customs thing other than if, as would be the case returning to the U.S. from abroad, the price is within the gift allowance limit and you can get someone to buy a unit here and carry it back home when they return or visit Ireland. Getting a used unit is risky because, unless the original packing materials were kept, the possibility of damage to the scale is a worry if it isn't carried by hand.
You should also be aware these dispensers are a convenience, but not required. Indeed, some shooters have observed that accurate volumetric dispensing actually gives them better groups. It has been suggested this may have to do with the powder picking up or losing moisture weight from air, and that could throw weighed charge energy content off by a percent or slightly more. The other theory I'm aware of has to do with packing density affecting burn rate in a compensating fashion.
The above seems to be mentioned more with some powder and cartridge combinations than others. Nobody I know complains about weighed loads from an electronic dispenser they own, but I don't think I could accuse most people I know of testing ammunition with a lot of scientific rigor. So this is all somewhat speculative.
When I want a maximally consistent load I do both. I use an electronic scale with enough capacity to weigh a charged case. I tare the scale it with a primed case, dispense the powder from a measure, and then note the charge weight displayed. I'll do 30 to 50, lining them up by their measure-dispensed charge weights in 0.1 grain divisions. I generally get a nice bell curve shape I can identify from the lined up cases. I then keep the center of the bell (usually the most or close to the most cases), dump all the powder from the other cases back into the hopper and tap them and visually check them with a light to be sure all the powder grains are gone, then do them over. This time I keep only the ones that match the bell center value I found in the first pass, and redo the others yet again.
It's much bother, but if you want to eliminate weight and volume both as variables, that's the only option I've found. Neither dispensing by volume nor weight alone is always best, though spherical propellants tend to do both at once without really trying very hard.
