Weird Viewmaster

I was in a charity shop today and found one of the "Model C Musical Viewers" shown on this page, boxed and with a few reels, for £25. I'm VERY tempted to go back and buy it, since it's apparently very rare, and flog it on to the collector's market, but I have no idea if there's actually a market for them that would raise enough to make it worthwhile. While the web site suggests high prices I can't see anyone actually selling one to give me an idea of pricing.

Anyone got any idea?

Inkjet cartridges

The shop where I saw the musical Viewmaster (see previous post) also had some unopened HP cartridges at £1 each; three tricolour HP 136, and one black cartridge with no number. Since I couldn't remember which cartridges my Officejet takes I took a chance and bought them; it turned out that they aren't the right ones. Further research says that the colour ones are for Deskjet 2300 series S and Deskjet 5440 series S, I'm guessing that the black one is for this model too.

Before I try to flog them on ebay, is there anyone here (I'd better say in the UK only) who's interested in them, and would like to get them at cost plus postage, which would I think be £6.80 total? No idea of expiry date, this was presumably on the box, which I don't have.