How about a Jet Boat ? Better alternative i think. I've often thought about buying one but i'm not sure i'd use it enough. Much the same
as pinballs in my opinion.

A jetboat starts at $37,500 and goes up from there.

http://www.jswpowersports.com.au/seadoo_boat_speedster_150.html

or

http://www.jswpowersports.com.au/seadoo_boat_speedster_200.html

A 2013 Jetski is very very quick. 115 to 120 kilometres per hour.

http://www.jswpowersports.com.au/seadoo_gtr-215.html

You can pick up the latest n greatest jetski for only $17,250 on trailer with all rego n lifejackets etc etc. Ready to go.
I have waterskied behind my jetski's and they can easily pull 2 x ski-ers out of deep water no problem.
The best fun ever.  The benefits of living in sunny QLD is that u can go all year long, even in winter no hassles. Even if it does get cold, u just wear a wetsuit and wetsuit boots. No hassles.

The 2 things i have alweays loved is Jet Skis and pinnys. Cant go wrong with either. And no one ever says jetskis or pinnys arent fun to share.
I am sure there are others on here who already have jetskies etc, maybe even a ski boat etc.