Rats, man I just sold a beater 1x12 cab yesterday. However, the price it sold for was $120, which may not constitute "really cheap" (despite that the EV speaker in it costs $229, to buy new). I'd watch craigslist, that's where I had mine listed.

In addition to cabs themselves, some little cheap ss combos come with detachable speaker connectors, so that you can attach the speaker to a different amp, like the head you describe. If you got something like that then the amp part of the combo could be a backup if you ever had to have your tube head worked on or it was otherwise unavailable.