Why do you want cheap? i bought the iso 60 mf light, but decided to move on to a ti sp sr. Make sure you really don't want a better racket, because you might as well get a good 80 dollar one you can use for a long while instead of buying a cheap rackeet then deciding you wnat a better one (as i did, lol)
He just wants a cheaper one for a spare racquet just in case. He isn't interested in spending a lot of money on just a spare.
Aaron, One of the things that you should consider is whether the other manufacturers like Winex, Yang Yang, Pro-Ace, etc. have similar racquets as usually their prices are lower than Yonex. This was what I did when I was looking for a back up racquet for my Yonex ISO-600 early last year and wounded up with Winex and was impressed enough with the quality of their racquets to become a distributor for them in West. Canada.