Most County extension offices do soil testing themselves, here. It costs $5 per sample for pH and soluble salts readings.
Or you can buy reasonable test kits at most garden centers, a 10-test kit is about $12 and then you can test the soil in different parts of your garden as well. They didn't used to be too accurate, but the new ones have the test agents pre-measured in little capsules for you, and we tested them against the fancy electronic meter at our Extension service with good results.
