Buying timber online?

Hey I wonder if you can help,

I have a project idea for the garden that requires 10 or so 8ft long poles 2-4 inches in diameter - I'd prefer unfinished, like little tree trunks. Otherwise pressure treated.

I've been googling away but I'm obviously not getting my search terms right because I can't find anything.

Wickes and b&q only seem to have planed timber.

Do you know of any sites that sell these reasonably cheap?