It can be for yourself, your home or maybe a gift for someone else.
For me it a dishwasher! Even though DP works away all week and eldest (that was still at home) has just moved out so there's just DD and I most of the time, but I've always wanted one.
I thought for 2 of us it would maybe be a waste of money, but DP took a cupboard out so we could fit the dishwasher in, just a slimline, but OMG I LOVE it!
It really was fantastic over Christmas and I've washed every single bit of crockery/glasses/pots in it and now they're all sparkling!
I don't know why I waited so long 
What have you bought that made you or someone else extremely happy?