Hey there, I'll answer your questions as best as I can.
First- Any truck can have a rust problem regardless of what state it is in. You could probably make an argument that some CA trucks closer to the ocean and salt air are more exposed to it than others, but there's no guarentee that any truck spent its entire life in one geographic area to be safer than another one... Basically, you have to check each one out.
Second- If you're thorough when you're looking, you can look for rust yourself. The biggest areas you want to check are on the frame, around the engine, the exhaust system, the cooling system, and obviously the body.
Your budget is plenty to find a nice 1st generation Tacoma. If you take your time and don't rush into anything, I have no doubt that you can find a nice truck that you'll be happy with. Buying from a dealerships has it's advantages and disadvantages. The advantage of a dealer is that they have laws they have to obey when they sell a car. For instance, the brakes must be at a certain thickness, the safety equipment must all function, ect. Then again, you generally pay more from a dealership than from a private party.
If I were you, I'd start looking in Auto Trader
.com and see what you can find... Good luck man!