Need just one cheap spare rim and tire

A space saver spare from a 90 Crown Vic or similar could work too but... Thats a very old tire to put your trust in. A used OEM steel wheel is probably the better choice.
And by the way, It'll be wise to have a lug wrench that fits your lugs. Avoid a "DOH!" moment ( yeah I did that ). OEM was 7/16". Your later is 1/2".