Games on Demand's latest additions are all about two types of orbs: agility and katamaris. The 6GB Crackdown is reasonably priced at $20, with the "Getting Busy Bonus Pack" DLC permanently reduced to 400 ($5). Those looking for a cheaper solution to obtaining Crackdown are advised to permanently borrow the copy their Spartan-obsessed buddies purchased for access to the Halo 3 beta years ago.
If you happen to live in Japan and are interested in collecting a single, incredibly huge sphere, Beautiful Katamari is now available. Helping the Prince keep his egomaniacal father happy will cost 2000 in Japan -- there's no word on a global release yet.