No such thing as an A3. It was either an A, which was the original model, or it was an A100, A101, A102, A103, etc.
If it was the former, it's worth something as a collectable, not necessarily as a performance instrument. If it's the latter, it's basically a B3 with internal speakers and very worthwhile.
As for the piano, I've got two uprights in my garage and one in my house that were all given to me for free.