I'm guessing that none of those will be less than £100 new. The lesser version of the drill is £100, minimum. That's what I paid for mine.
All that lot, new could be over £1200?
Looks as though, if he's that well kitted up, then some of the stuff could have been worked hard, but that doesn't matter too much, it's quality kit, and looks to have been well looked after.
Taking into account that there is presumably no guarantee on it, I'd say.....
......Work out new price, and offer a shade over half, for starters, going no more than three quarters. Not worth three quarters of new, IMO.
A bit less than three quarters, max.