While many such places are legitimate, the key question is if they're worth it.
Since the time is 11 years, the money has almost assuredly escheated to the state. If you know the state(s) where dad lived at the time the IRA might have been opened, you might be able to search on-line databases for the amount.
When you are a Bear of Very Little Brain, and you Think of Things, you find sometimes that a Thing which seemed very Thingish inside you is quite different when it gets out into the open and has other people looking at it.
--W. T. Pooh (aka A. A. Milne)