Does anyone know of (perhaps even able to reccommend) good waterproof socks that are cheaper than Sealskinz?

5p plastic bags?

The Aldi seal skin copies are good, I have a couple of pairs.

Worth putting your longs over the top to stop water running down into them – although if it does it gets warmed up after a while!

Second the Aldi ones ,seem pretty good so far ,regularly have to ford a local river or too lately after the rains here in Eire

Neoprene socks are usually cheaper than Sealskinz. I think neoprene is better, because its are actually waterproof. Though can get sweaty, I wouldn’t wear them unless its really cold and wet.
I have these from Rooster, £12. https://www.roostersailing.com/pd/Neoprene-Wet-Socks_105342.htm

Excellent – I’ll try them both! 😀