Hi Jam Monkey!
I'm sure you must have already checked popsike.com. The last few listings for that particular single have seen it go for $129 USD (May 2010) and $103 GBP (Feb 2010). Both in VG++ condition and with Caterpillar label.
I managed to get a hold of that single and the Keep Yourself Alive reissue with God Save the Queen and Lily of the Valley for $1 and $2, respectively, PLUS SHIPPING. :)
I don't think I'm gonna get a better deal in anything in my life... ever.
And If was in an online record shop. I guess the seller didn't know what he had in his hands :).