Go to your local Golf Galaxy, ask to try out the different Cobra drivers that
are on sale for $250 (1-2 year old model), try out a couple shafts on them that won't result in a price increase.
That's my best advice on sticking cheap. Next ones would be an older stealth model for like $350, then an older Ping G430 model for $400. I don't like to buy used stuff though.