Yea I can guess balloons at festivals are absurdly expensive. For home use, search for a brand called "Purewhip". There's basically one vendor in the US (and a few in EU) and it is noticeably cleaner that ALL other brands (including the way overpriced ISI)... the "residue" is thought to be just vegetable oil used to prevent rust on the inside of the cartridges, and can be mostly eliminated by inhaling from cracker through a cotton shirt or other filter.... ANYWAY Purewhip while still having a little of that, has WAY less that ALL other brands... and from the vendor, who has a shipping location in FLA and one in CALI you can get cases 25 boxes of 24 cartridges for about $170, shipping included, as well as all sorts of supplies like whipped cream canisters for administration... though I always waste some with those screwing the thing on... a cracker and punching-bag balloon seems to let me get 100% of it. Oh and that vendor after you buy from him or register will around holidays send you a link to a special page for an extra discount, putting a case at more like 160. Shipping is fast too... 2 calendar business days from Florida to me in N KY. Pretty amazing, if you ask me... not spamming... just a fan.