The Intermatic IG1240RC looks to be quite a capable device at a very reasonable price. An outfit called A+ Supply Co. is selling them for $55.95;
http://www.aplussupply.com/intermatic/pg5000/ig1240.htm.
The Intermatic unit is listed as UL 1449 2nd Edition compliant. From what I have read, this is both a safety and a performance standard incorporating both ANSI & IEEE testing proceedures. This also appears to be the de-facto standard for the suppressor industry.