Pulleys?

[ffutures]

I need to get some pulleys that will clamp to the edge of a table. They are ludicrously expensive from all of the usual laboratory suppliers, but I have a feeling that there must be other uses for them. Basically, I need to hang up to say 3kg of weights over the edge of a bench on a string or wire - a metal pulley wheel is probably preferable, but plastic would do if the price is low.

Here's a picture - unfortunately this is from a US source, I can't find a cheap supplier in the UK



Anyone know of a source for something like this in the UK whose price is vaguely realistic?