It is canon that Hagrid lives in a hut. It is full of items his size: a large bed, large cutlery, etc.
- Where do wizards generally purchase normal things?
- Where does Hagrid find things his size?
It is canon that Hagrid lives in a hut. It is full of items his size: a large bed, large cutlery, etc.
We don't know where he purchases his clothing, but the possibility is raised that he knits them:
Hagrid took up two seats and sat knitting what looked like a canary-yellow circus tent. "Still got yer letter, Harry?" he asked as he counted stitches. (Philosophers Stone)
We don't know what he is knitting, but being it's very large, it's possible it's an article of clothing for himself.
In fact, specifically regarding his socks, it is explicitly stated he darns them:
A light rain had started to fall by mid-afternoon; it was very cosy sitting by the fire, listening to the gentle patter of the drops on the window, watching Hagrid darning his socks and arguing with Hermione about house-elves – for he flatly refused to join S.P.E.W. when she showed him her badges.
‘It’d be doin’ ’em an unkindness, Hermione,’ he said gravely, threading a massive bone needle with thick yellow yarn.”
So we see he knits his socks (although its possible this is just a repair), and it's probable the same is true with regard to his other clothing.