The issue your fighting is this:
https://www.taiwangun.com/en/electric/cm-028c-cyma
Same gun, brand new, and without 2-tone if you have your ukara for £35 less than your asking price (from last i checked just before writing). The general (although not exclusive) rule of thumb is ~60% of retail for a secondhand item.
This thread for sure is a strange way of evaluating the classifieds, but it can work well if you take it in the spirit of the same kind of banter youd find in your average airsoft safe zone.
You are of course free to ask whatever price you like, and you may be able to sell just fine, but at least now you know what you're competing with.