Cases that came up easily (in the same search result) ran $46 - $52 US - a couple of choices.
I did find:
Monster - a "user's description" of mounting stuff in a $49 case.
The part number given indicates a 145 Watt "Micro ATX" power supply. The "micro ATX" part of it describes a "form factor" that should be standard enough to fit interchangeably with any other with the same description. There were a couple of lower powered units listed, but you'd probably want at least what came in the machine. If you get a good price, a little more won't hurt you, but I doubt that you'll find anything over about a 180W in this form factor - for a bargain price, at least.
These are all "mail-order" so they should be able to get them to almost anywhere - but don't forget the shipping charges when you're figuring what it will cost you.
If you're just wanting to fix this one up "until..." you might find a "used" power supply at almost any (local?) place that does repairs - but it's sometimes a good idea to know what the "mail order $$$" is before you talk to these guys.