This is a tough hobby to continually get your "fix". I think if you limit yourself to just Ruth and Gehrig photos you may continue to be disappointed. I've limited myself to mostly hall of famers but I have purchased outside of that limitation if I like a shot or if the photo is from a certain photographer.
I actually do the same thing as Mike. I spend hours searching ebay and sometimes find something special. I actually think Mike and my techniques (or obsession) are too close as I've seen him post many photos that could of been in my collection if I was just a few seconds quicker.
A year ago at this time I was picking up so many photos on a weekly basis I thought I was going to go broke. Now I wish I'd bought some I passed on, as right now there are slim pickings, but I do believe things will pick up again.
The fogel/yee book is a great resource but I believe this forum is the best resource your are going to find. When I was able to find my fogel/yee book for a reasonable price ($36), I realized that I already knew a lot of what was in that book because of this forum and the great people here willing to share their knowledge. I would suggest going back and looking at old posts and especially the monthly pickup threads as you won't only see some great photos but there sometimes is some great information about them.