Many, maybe most of us, have found that lab testing can be totally wrong. Maybe some labs are good for some critters, but I don't know.

The cheapest test is taking paracides and looking in the toilet to see what happens. Since everyone apparently has parasites, might as well start killing the nasty things asap.

In the link below is a quick easy way to find out if you have at least one kind, namely tapeworms.

What helped me in case any of it can help you:
//www.curezone.org/forums/fm.asp?i=1522290#i

The question is not what is the cheapest test but rather which is the most accurate. Use Metametrix GI Effects panel #2105, this panel tests for parasites, fungus/yeast and bacteria. PCR testing is the only accurate test, you will be wasting time and $ with other tests.