I paid 25e for mine last year, which seemed to be fair market value, but the price of r9 20/10 bo staves have increased in some collectors eyes with some r9's going upwards of 85e or so a piece. It's dependent on the collector though.
As much as I hate to admit it, I agree with Dealer. There has been a rash of interest in r9 20/10. Why? I don't know, but I too recently sold a handful of random attributes (Nothing special) for 100e a piece when averaged out.