Hi,
I am on my second tornado, and use them primarily for fun sailing in club races. If you are not going to compete in the strictly Tornado events, there are lots of bargains out there. As Greg says in the above post, these boats are not competetive in Tornado events.
However, there is so much to learn on these boats, that, in my opinion, you could go on for some time before you need a truly competative boat.
I just purchase a well equiped 84 Reg White tornado, that had been upgraded to Marstrom everything, for $3k. This was an outstanding deal for me. You can see the add for the boat on
www.tornado.org. Since new boats are $20k or so, this is a lot of bang for the buck.
Also, you may want to consider a Prindle 19. It is a simillar, design, but is only 8.5 ft wide, and is a production boat. The layouts are simillar (to the old rig Tornado) so anything that you learn on one, you could apply to the other.
Both boats are extremely fast, and for the most part, well behaved. They don't typically pitchpole and do other bad things like some smaller and more popular boats.
So, here are some prices that you might expect to pay.
Marstrom (the best, competetive) 8k & up
Reg White (OK, great club race boat) $3k -$7k
Newer Sailcraft - late 80's $3k - $4k
Older sailcraft, pantercraft, etc. (stay away unless you get real cheap)
Prindle 19 $1.5k to $10k
Also, if you can find a boat that is owned by someone in the Tornado racing groups, you are better off. These guys are more meticulous than the typical beach sailor.
Hope this helps