Just seen that there is a CO2 inflator in Aldi this Sunday (3rd) for €7.99. Might come in useful for anybody with kegs that doesn't want to go the full hog with a canister. How good it is I don't know, but i thought i'd throw it up here just in case. I think it only works with a threaded disconnect as its suited to presta/schrader valves. I haven't got a keg system so i don't know about using it but i'm sure somebody will be able to explain.
Link - https://www.aldi.ie/en/specialbuys/sun-3-may/products-detail-page/ps/p/c02-inflator-with-cartridge/
Similar to - https://www.thehomebrewcompany.ie/co2-charger-for-cornelius-keg-i-cartridge-16g-p-63.html