The price is here! for the Kerry-All ride-on mower cover.....
reddragon sent me some measurements (I guess he can tell you the make and model), but it's 72" long, 36" wide at the rear and 24" wide at the front, plus 42" wide on the middle to fit the deck.
The retail is $69.95 plus shipping (about $15 to most US/Canada destinations).
If I had a few orders, say half a dozen, I think I can get that cost down to $55.