I highly doubt those grinders will sell for those prices, but you never know. My dad sold his SDM-4 a few years back for $1800. I seen another mint one sell for the same. I sold my well used one a couple months back for $800 (looked about like the one listed for $2000)
If you think the markets there, id go for a SDM-4 or a improved RSII. Is there really that great of a demand for chain grinders? Not a lot of hand falling going on compared to 10 years ago. Plus, if I was in the market for a grinder, there is nothing wrong with a Simington. I know a lot of professional cutters using them. I feel like part of the reason guys want the Silveys is the history behind them. That’s what my old man used, I remember being out in the shop grinding chains with him when I was just a little kid.
The thing the Silveys got going for them is that they are really consistent and super smooth!
I have a Madsens catalog from 2008. Pro Sharp is listed at $2099.