Posted By:
Andy BaranThere was probably a Keeler card produced as part of the 1894 Alpha Photo Engraving set, but none have ever been found. Keeler is on several team and individual Cabinet cards in the early 1890's, though none are regular issued "cards" in that they were not issued as part of a set for commercial use. Cabinet cards are essentially photo's that were glued to a cardboard backing.
I believe Hal's estimate of 4 Betz cabinets is probably pretty close, give or take 1 example. I would guess that one would fetch in the neighborhood of $15K if available, maybe a little more.