Hmm, maybe not the same Unitron 131-C.
The only one I can find on Ebay in the last few months was cell #C-617, different counterweights, the OTA had no labels on the tube and EPs were different (info as to sales via Terapeak).
You might be referring to the CN ad here but I don't think that's the same one as there is no mention of the cell serial number in that ad and there are no stickers on the tube. If the seller did add the stickers and the EPs then the price increase would seem OK.
But perhaps I'm missing a listing as I don't see any reference to an objective needing cleaning in any of them.