What records/brands should I look for?

[Bartman]

I just got about 250 old 78's at a storage auction for $20.00 and I'm wondering, what are some of the more rare records I should be looking for? This lot came with everything from Decca to RCA/Victor to Victor to Columbia. Most look like they've never been played and are in their original books/sleeves. Way cool find!

[Bartman]

I just found a record that is blank on one side and was custom made on the other. Is that rare or not? It says, "Recorded by KROW", "The Home Interest Station". It's got a typed in program line which reads, "Australia Calling" and the "sponsor" is "Lt. Thomas. W. Gavey". Way cool.