I have been wondering about this questions and not really sure of the answers. When you are looking to buy links are you more attractive to a deal where it is $10 and they are only selling 10 links. Or a deal of $5 and they are selling 20 links. Not talking PR or content here, just talking in general. Would you rather double the price for your link with twice as less of links. Or pay the lower price and have 2x amount of links.
Depends on what you are using the links for. Link text - This can help you quickly in the serps of msn. More links the better, PR doesn't seem to matter Traffic - Once again more links, better placed the better. PR doesn't matter if the site is related and the link is in a good place. PR - The fewer the links on the page the better. If they are only selling 10 links on the page it may be able to pass more PR (of course depending on the number of internal links)
If the site I owned was selling text links, I would sell 1/2 at 2x the price. Why? Less ads on the page. If I was purchasing, it would depend how many outgoing thinks there were already on the page.
It basically depends on the page where the links are put up. I mean if I am getting 20 different pages and a link on each for $5, then it is quite good. SZo basically the number of links on each page does count a lot. And much as you like PR cannot be counted out. Especialy if you buy it for PR. A PR 3 with a couple of outbounds might be better than a 4 with many outbounds.