Google seems to find nothing, but does anybody know if there is a way to get old iPhone IPAs?

I have an old iPhone 3G running 3.1.3 and I would like to find SiriusXM Internet Radio V1.4 so that I can use Sirius4Ever for it because the phone is too old to run 2.2.0 or the current version.

Does anybody know if there is a site like "OldVersion.com" for iPhone apps so I can get this app?