You can use a 'car fridge' or 'car freezer' as a cooling reservoir.
I use 2 of them, they cost around $50 AUD each and hold 20 liters each.
When I first started aero, temps were too high due to the submersible pump.
Changed to inline pump, worked great but being fussy and wanting to hold it at between 70 - 72f, I added in aquarium heaters.
I see the aero guys constantly going on about chillers and the big price tag attached, but it is much cheaper and effective to lower the temp and then bring it up with a heater instead of just a straight out $$$ chiller.
I probably should speak up lol
As for the fact that it is 12v or 9v designed for a car lighter doesn't matter. You can find plenty of adaptors on Fleabay and shops with up to five points that can plug directly into your wall socket. And also with a few extra sockets, you can wire in low voltage computer fans that are very effective and cut a couple of bucks off your power bill instead of inline fans =)
Good luck!
Jimmy.