A Baldwin Acrosonic piano from the 1940s to 1960s is best; later models may not necessarily be as good. Check the condition, regulation and tuning of the piano. Consider the price of the piano, cost of repairs and shipping charges before the purchase.
Check where the piano was stored. If the area was damp, the felt parts in the piano could get loose and hammers could get unglued, requiring costly repairs. Check the piano for bugs, rodent residue, moth and roach casings, pet hair and spiders. Find out whether the piano has been regulated; regulation is an important and costly process. Have a tuner or technician check whether the piano can hold a tuning.