I'm happy to tell you that solar panel cost has been coming down slowly but steadily for a number of years, but now with fuel prices affecting everyone, they are in all liklihood as low as they're going to go for quite some time.
Just a few years ago, a good quality PV solar panel cost thousands of dollars and hobbyists used to pay tens of dollars for pathetic little factory offcuts to they could experiment with solar electricity for science fair type projects.
Such solar panel offcuts could only produce enough power to run a tiny lightbulb or a toy electric motor... enough to demonstrate that the system produced electricity, but nowhere near enough electric power to do anything useful or practical.
But today, a small 5 watt solar panel can be bought new for as little as $50 USD, while new 80 watt solar panel sells on eBay for $400 USD. (Priced in March 2009.)
Those are decent prices, but do be sure and shop around. Compare brands, models and prices of solar PV panels before you reach a decision which type to buy for your own solar electricity installation.
Make sure the prices you compare include delivery of the solar electric equipment right to your door, unless of course you will be collecting them yourself from some local seller or store.
And when assessing your solar panel costs, be sure to take into account the cost of your whole installation, including wiring, switches, power plugs, lighting fixtures, your charge regulator and any DC/AC inverters that convert your solar electricity to 110 volt (or 220v) mains power.