I don't think it's worth buying a pulley if you don't have one , I had 3 Victa ride on mowers that were missing the engine pulley and when I priced just the pulley it would have been $50 to $80 , so in all cases I just bought a second hand ride on with the pulley for $50 to $80 ,I've seen a few Victa ride on mowers for free.
A better idea would be to buy a cheap working ride on mower as all the ones I've repaired lately never made any profit from them.they were sold for $250.