Stan,
The RC Ammo in Uruguay [from the outfitter] is running $12/bx. these days, used to be it was a couple of $ less. Sometimes there is still a bit of squiggle room, but one has to remember that's where many of the outfitters are making their money. Like us here, they are paying somewhere from $7~8/bx. wholesale for the good 20 ga. ammo.
Changing horses, I purchased a number of flats of Italian Centurian 12ga. ammo last year, mostly because the price was very attactive. It is all 3/4 oz. loads of hard #8 shot at 1400 fps. I find it throws good patterns on the grease plate & breaks bunker targets quite well, but find it a bit abrupt or 'punchy' for repeated clay target shooting in some guns w/standing breech. I also used it on dove in W. TX on several dif outings w/very good results. In the dove field I never noticed the recoil sensation, but we all know how that works;-)
With school about over, I'd hope your grandson is able to both lend a hand w/that dove field and to do some sporty clay target shooting w/you during the summer months. Given the chance to hone his shooting skills, he may be good competition for you come Sept. 1