@Aphex5 As long as the app hasn't been withdrawn from sale, you should be able to see it from within the normal place for past releases… (oops - I'm wrong since that's the iOS app store… Hang on - let me see if archive.org is crawling the public web pages yet…)
Yes - presumably the developer and Apple have retained the details, but neither is generally available when you need them (and the costs to retrieve data is prohibitive in many cases).
I noticed appshopper.com keeps pricing history, which is kind of handy, although not exactly what I needed (e.g. appshopper.com/mac/productivity/cobook)