I think we got that. This is not a high-precision ciircuit.
Ken's circuit is about as simple as it's gonna get. Once you get the parts, it'll be easy to assemble. You do know how to solder, don't you? If not, it's easily learned, and this is the perfect project to learn it on.
About getting the parts, not sure Radio Snack will have all of them (I doubt they'll have that transistor and the Sonalert). Is there by any chance a real electronics store near you? If not, there's always mail order, though that's a pain if you're itching to go now.