"I don't use antifreeze at all, so I guess I can't answer that."

Antifreeze, coolant....tomato, tomatoe. :-)

"There is though a white build up under the oil cap and definately no leaks I can see on any pipes. I'm guessing that doesn't sound good for the head gasket?"

The white buildup *could* be condensate from short trip driving. Or it could be the result of coolant and oil mixing.

"definately can't afford the $700-800 repairs...what are any of your thoughts on that stuff you pour into the cooling sytem that adheres to the inside, hopefully plugging any leaks??? Worth a try??"

I think that the best thing for you to do, is to take your car to a mechanic and have them pressure test the cooling system. This is the only way to know, for sure, what and where the problem is.

If the problem lies with the headgasket, the stop leak stuff won't help.

One other place to check for leaks is at the heater control valve. Does your heater work? The valve is mounted on the firewall near the gas pedal, and is accessible from behind the driver's kick panel in the center console. A quick check consisting of removing the kick panel and pulling up the carpet under the pedals will reveal whether coolant has been leaking into the floorboards. I think that you would have noticed this by now, though.