If the tread on the other 3 are good, you can just replace the one tire with an identical tire, either new or used. You just need to be within a few 32nds of an inch of tread depth. You may be able to find a used one that matches this criteria for about $20-$25 from Hooten, Rays, or one of the other used tire places.
You can also shave a new or used to the right depth.
$73 is not a bad price. They are $64 at TireRack. You can use that as leverage. That is probably where they are buying them for $50 something each wholesale.
TR warehouse is in Sparks, and you can pick them up there and take them anywhere for installation if you want. Sid has been known to match TR price if you ask and mention Debbie. Don't mention me, you'll pay extra.
