Advice on purchasing multi-signed baseballs

[glchen]

Hi, I'm new to this part of the forum. I typically just buy cards, but I'm considering expanding my collection to pick up a few baseballs too. In particular, I'm looking for a Ruth signed ball at a reasonable price.

Single signed balls seem to be much more expensive, so I'd be satisfied with a multi-signed ball with Ruth as long as the signature is fairly clear.

Is there any advice that experienced collectors have on this? I've read some of the threads, which say that single signed is much more expensive than multi-signed, and that I should purchase a UV cube to store it in and avoid light when possible. One of the questions I have is regarding how do you know whether the ball is reasonably priced. For cards, there is VCP, so you know roughly what you should be paying for the card. There doesn't seem to be the same thing for balls, although there is SMR pricing for single signed. Any other advice on this would be great. Thanks!

(Oh, and I would only purchase a ball that is authenticated by JSA or PSA/DNA and not STAT, etc, so I know about that.)