How much is your 18 jeweled serkisof pocket watch worth?

Depends very much on age and condition. The 3602 movement was produced by Molnija (USSR) from about 1947 to a few years ago (if/when production ceased is not clear). A variant on the standard soviet open faced Molnija was a 'badged' Serkisof with an embossed train & 'Serkisof - Demiryolu' (iron road) on the reverse. This was apparently for the Turkish State Railway. I have seen photographs of a model which features the Turkish state symbol, the embossed train and the logo (TCDD) of Turkish State Railways, these appear to be the least common. I have a recent example which claims to be 18 jewel but is powered by a bog standard Chinese 17 jewel wristwatch movement. The case is awful staybright rather than base metal and the quality poor compared to Soviet examples E-bay prices range from under £10 upwards, some optimists put them up for ridiculous prices but those that sell seem to fall mostly within a £20 - £50 range. Not a very precise answer, but without complete details of the watch it is the best possible.