If you are looking for an ungraded one in c7-c8 then you should be looking at around £120-150 max. Mint ungraded would likely be closer to £200 (perhaps a bit less) with a high scoring graded one being closer to £300.
Bossk, like many other characters on Trilogo cards, has a habit of not turning up at all for 6 months and then all of a sudden 6 will show up in the space of a few weeks, definitely worth waiting for a good deal on one instead of overpaying.