How much is a reasonable monthly fee for a banner ad on the home page of a PR2 website that gets 2500 uniques a day?

Many of those visitors may not visit the home page, so also any idea what sort of fee would be reasonable for a site wide banner ad on such a site.

The company wanting the ad, sells products that relate to the sites content, so its very relevant and targetted for them.

I just have no idea whether I should ask for $5 a month, $20 a month, or more or less?

If anyone could give me any guidelines, so I dont sell it short, or on the other hand ask way too much.

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