Well, there is the cost of just doing the basic inspection, then there is the cost of doing the little things required to keep it airworthy and/or in top condition. (Not necessarily the same thing.)
A basic inspection for my AA-5, which would include oil change and filter, spark plug inspection and regapping, magneto check, etc. (the basics) is around $1000 for various local shops. Of course, there are always other compliance issues and things that require fixing, including (as examples) static/transponder check ($350 or so), ELT battery replacement, baffle and seal repairs, gasket replacement, wheel bearing maintenance, brake maintenance, minor structural work (crack repairs, etc.) On a good year, I can get everything done for $1500-$2000. Having a low time engine is very helpful in keep annual bills low (for now).