Kent Cartridge Canada in Markham ( Google "Kent Cartridge Canada" for a phone # and address) usually has some Gamebore loads in stock. Although they don't sell at retail, they can direct you to a dealer that either stocks their brands ... or who will bring them in for you in case lots.
"Black Golds" certainly are not recoil friendly, as Henry states above ... I've used them - and they're fair snappy !
"White Golds" are a little tamer. Don't know where you get the "30% more pellets than lead" from ... I don't see that on Gamebore's web site.
"White Golds" are lead ! They are a premium competition cartridge and are a little pricey.
If your looking for a very good load with a less recoil, I'd recommend Gamebore's "Blue Diamond" in either the 24 gram ( 7/8 oz. ) or 28 gram ( 1 oz.) They are available in 7-1/2, 8 or 9 and feature the B&P style Gordon Hull which most concur, seems to provide a little less felt recoil over conventional hulls. They absolutely crush targets. For Skeet as well as Sporting& 5-Stand at conventional range ( 30 yards or less) I also like Kent's "Velocity" International load of 24gram 8-1/2's. Great practice load with very little felt recoil.