How much is a blog worth?

There is a blog up for sale, at auction, and I wonder if you can predict how much it will sell for. (I am not going to give out the URL, because I don’t want you to see what the current bid is, but if you think you might want to buy it, give me a shout and I will point you in the right direction.)

Here are the facts:

The blog is about blogging.
The blog is very well designed, was launched in February 2007, and has more than 2 000 RSS subscribers (people who read it by subscription). This number has been growing at about 100 new subscribers per week.
There are 33 posts, and the owner says that readers do not expect more than one post a week. The 33 posts have more than 950 comments, which point to a loyal, and dedicated, readership base.
There are 103 000 page views per month, and 75 000 unique visitors. For those of you familiar with Google’s PR, this site has a PR of four. The implication is that once Google recalculates PageRank, this should move up to five or six. The site has about 20 000 inbound links. Technorati rank is in the top 5K, Technorati authority is over 700 and Alexa rank is about 40 000.
The site’s revenue is $175 per month. This is made up of $20 from AdSense, $100 from direct-sale ads and the balance from affiliates.
The owner of the blog is selling it because it does not align with his core company. He has no idea how much a blog like this can go for, and I think he opened the reserve at $500. He was offered $2 500 for an immediate sale, but he chose to remain at auction. The auction lasts 15 days, with eight more to go.

How much do you think this blog is worth? How much would it be worth if it was geared to a South African audience? How much would you pay to buy it?

I will post the final sales figure once the auction ends, but please post your guesstimates in the comments.