For a budget-minded adult with idle curiosity to satisfy, there are IQ test books you can buy and self-administer. I did this many years ago, and while the results are not anywhere near as reliable as formal, proctored testing with a trained professional, I still found my results to be within a few points of my DD's more formal score, and within a few points of the result predicted by my (pre-1994, when it was highly correlated with IQ) SAT results.
There is a proliferation of free IQ assessments available on the web, as well. I don't know of any I would consider reliable.
