RegSupreme, only $13 (£6.50), is a basic, no-frills Windows Registry-cleaning tool.
RegSupreme includes a Registry cleaner as well as a Registry compactor, and is in essence a scaled-down version of its bigger sibling, jv16 PowerTools.
In RegSupreme you get only two levels of error detection, safe and aggressive, as opposed to four in jv16 PowerTools. And the program has almost no extras; the only one of value offers a way to search for specific keywords in the Registry (e.g. RealPlayer).
On the other hand, the inexpensive RegSupreme has a built-in backup tool and gets the job done. Like jv16 PowerTools, RegSupreme supports every version of Windows and comes with a full-featured, 30-day trial.