I am actually more of a razor guy than a knife guy. I typically pay $5 - 10 for razor hones. I never saw a Spike branded hone before. I do have both an Olean and a Moravia Spike SR, plus a Bow Steel SR that looks like Union Cutlery made it.
Here are some of mine:
Your hone looks in excellent shape. I might personally be tempted to pay $20 if I found it on my vintage prowl. The right Union Cutlery focused buyer might go much higher, but razor hones are synthetics. Natural stones and high quality modern synthetics command the high prices.