Open Question: How Much Should I Charge for a single ad on a blog post?

I have a personal website that I use as a promotional tool for myself, but also have been using it to blog about various things. One particular week, I recapped my cross-country road trip I took when moving from Boston to Los Angeles. Recently, an advertiser contacted me about placing an ad for his hotel chain on one of these posts. He's asking me for a quote on a text link, a banner or a widget. He just wants to place the ad on this one blog post, and not the entire site. I had no intention of ever selling ads on my site, but I am not opposed to it. I've tried to do some research on advertising rates and where to start, but I'm still a bit confused. Any help would be greatly appreciated, thanks!