Not having all the details, I would venture to say that:
PR4-PR5 with 300pages - $20 to $35 for single linke, maybe up to $60 for site wide
PR6 - $35 to $50 for single link
PR4 - $15 to $25 for single link
These are the prices I've seen.
Hi Jim,
Those prices seem pretty high. If I were to offer you a PR4 site with 300 pages would you pay $20? (If the answer is yes, please PM me immediately!) Consider what the market will bear. My advice for what it's worth would be to start at half that and see if you fill your spots. If so, give your customers 3 or 4 months at the original price before raising the price on them and raise the price for new subscribers. Remember that it's easier to keep customers than to find new ones.
If you don't sell your links, you'll know your price is too high.
You are in this for the long haul. Just find a median price you can ive with and adjust your price as the market dictates.