This definitely depends on budget. There are eight or ten companies that would be happy to make you shocks. Off the top of my head, I'd go for works.
IF you go the "custom" route, the prices start around $300 and go skyward from there. the prices kinda plateau around $1500.
There's a big problem finding shocks for mopeds. The bikes weight is so light, that finding shocks with the proper spring rate, and damping levels isn't easy.
The lightest bikes I can think of, that have dual shocks, are the honda monkeybikes. Any "real" motorcycle I can think of (GS250, rebel, nighthawk 250, etc..) start around 300lbs. Assuming a 50/50 weight ballance, that means the single axle weight of the bike, sans rider, is as much as a whole moped.
.... can you tell I've put some thought into this?
The spring rate is much, much more important than damping. A bike with no damping can be remarkably fast, with a smooth rider and proper spring rate.
How much of a market would there be for moped shocks? the only real sticking point is that the smallest I could see them costing is $2-300.