If your definition of "affordable" is close to mine (i.e. "free"), then take a look at Eagle. If it's close to Leon's, then by all means take a look at Pulsonix. I can't see spending $3000 to design a few hobby PCBs that will cost me a total of less than $200. But if you make a living at it, that's a different story altogether. Get the best tools you can for your profession, get what you can justify for your hobby.
I'm using Eagle, and it's pretty decent, once you get used to it. There are plenty of non-intuitive bits in its interface, and the help system is, um, (how can I put this nicely?), sub-par. Once you get the hang of its interface, you can do a lot with it. But the learning curve is a bit steep at first. There are a few tutorials on the web (do a google search) that will help a lot to get you started. Also read the newsgroups hosted on
CADSoft's website as well as this forum. Lots of good info and people who can (and will) help.
Hmmm, I just re-read this before posting, and I feel like I'm doing CADSoft an injustice. I don't mean to make it sound like Eagle isn't suitable for professional work. If I had to design PCBs for a living, I think I'd be happy using Eagle, now that I'm used to it. I've seen Leon mention that Pulsonix's autorouter is far better than Eagle's, and I can believe that. But I just run the autorouter for entertainment, then rip everything up and end up routing everything by hand anyway.

Having never used Pulsonix, I can't say what else, if anything, it does that makes it worth $3000, as opposed to $400 for Eagle Professional. Eagle is a pretty darn good tool, and Pulsonix had better be pretty fantastic to justify costing 750% as much. Maybe it is. If I started doing this for a living I'd at least take a look, but I could certainly be satisfied with Eagle.
Keith