My recommendations:

Hobie-17 - cheap, robust, may still be good pockets of one-design, singlehanding but can take crew. Maybe a little heavy but as stated before technique helps.

Mystere 4.3 - you've heard all about that. Sounds like some good deals and people around your area.

Taipan 4.9 - lots of same reasons as the 4.3, but fewer around for one-design.

Wave - great fun starter boat, may get boring.

Hobie 14 - cheap, robust, great fun boat, good skill enforcer, light, can have in uni or sloop. Some pockets of one-design. Even when you move on to another you might keep it for fun.

For your money the 4.9 may be harder to find. I really like the 4.9 as a boat for all seasons and reasons, but their numbers are small in the U.S. so far. Hobie 17 would be a good choice starting out.