How much is a four wheeler that turns into a jet ski?

I'm curious, can you give me an idea of how much a vehicle that can transform from a four-wheeler into a jet ski might cost? I understand it's a specialized and possibly high-tech product, so I'm wondering if there's a rough estimate or a range of prices I can expect to encounter. Are these types of vehicles typically sold by certain manufacturers or is it a niche market with various price points?