There are several Exmark Lazer seats. If he wants exactly the one he has, and it is the "comfort ride" I think it was called, just bring the money.
For us, I went to TSC and Rural king etc. and looked at the varieties they had and bought one for about $100 that worked out real well.
Probably spent an hour drilling some holes making everything bolt up and work right.
I could have saved a touch of money ordering online, but there is something I still like about being able to look and touch the product, and if you will "feel" the quality before I plunk down the money on something like that.
The other Lazer needs a new seat now in my opinion, but the lady running it seems happy enough so until she says she wants a new one, it will just run with what it has.
Has he went to an upholstry shop and asked what recovering it would cost. I did not have the deluxe seats, but the base model seats and they can be recovered by a good upholstry shop.