It would be unique, so in theory you could charge what you like!
You're knackered either way really. Convertiing an Aerotop to manual is gonna cost £5000+ (I asked JIC once - they said they stopped investigating once the price got to £5000, so it's at least that), and taking the roof off a hard top is gonna balls up the rigidity. Although I think Scooter's plan does look pretty well thought out - good starting point at any rate
I'm just wondering about the US manual Aerotop though.... *ponders*... what would you need for that? Assuming the body shell/chassis is the same for both LHD and RHD cars, that means the pedal box could be fairly easily swapped over (as it's the same body/chassis for both markets and was designed to have it on either side). After that, all you need is a RHD dash...?
I wonder if simply convering a LHD car would actually be easier. Dunno about cheaper, as you've got to ship the car over here obviously, but the only labour would be moving the pedal box and the dash...? Parts cost would be just the price of a RHD dashboard!