I have a couple. So does Tim.
One of mine is a suped-up Mako with a hot-wound motor, a reinforced hull and bulkhead, an aftermarket "long life" battery, and several external modifications, including a set of stainless steel propeller blades that increase efficiency and speed. My other is a similarly-modified Apollo.
Tim recently purchased a pair of SeaDoo knockoffs from eBay - the orange and black ones rated to 160 feet, I believe. I don't think he's done any modifications on them.
On my recent trip to the Bahamas, my wife and I used a set of orange and black brand-name SeaDoos.
The scooters that I'm talking about here range in price from about $180 (Tim's) to about $3000 (used price plus modifications) on my Mako. My next scooter will probably be a modified Gavin or Dive-X scooter, depending on it's specified use. Budget will be somewhere between $4k and $5k.
Personally, I can't imagine any more fun in the world than flying a hot scooter in full dive gear through an unexplored cave or shipwreck. I used to race streetbikes... Which is a ton of fun! I was once married to a porn star... Also a lot of fun!
Scootering? Trumps them both by far!
Historically, however, people spend the money and find themselves flying them a couple of times, and then they become dust collectors in the garage somewhere... Similar to other scuba gear, but even worse.
Are you sure that you wouldn't just rather go on vacation and rent a scooter for a couple of days? How serious are you in purchasing one? What's your intended purpose? Diving? Snorkeling? Riding around with the kids in tow?