I contributed my whole £2100 personal injury settlement towards our next family car after an accident, would be the most expensive thing i've ever Co bought.
As for personal, it would be a toss up between my laptop (i dont remember how much it was but i think somewhere between £250-300) one of my games consoles (ps3 a good few years back then a ps4, both were about £250 at the respective times) but the one which seems the most expensive based on actual function would be my headset for said consoles, which was also £250 but it the top of the range named wireless one, and after almost 5 years is still going!
Unless you count the money i spent on scumbag ex's, which to me is a waste of over £1000 over 2 1/2 years on ex1, and then another £600ish over 6 years on ex2. I did kind of learn my lesson in not buying big expensive presents, and so ex2 was just birthdays, christmases, and the occasional dominos pizza (just for him not shared, it was sent to him where he lived) although, at least ex1 did buy me birthday and christmas presents, albeit cheap or useless ones he already knew i didn't want (honestly think it was intentional) where as ex2 never bought me so much as a birthday card, ever.