Trouble Valuing Game Used Signed Ball
 

Hi everyone! This is my first post as I found this site when trying to find the best way to valuate something I'm potentially going to buy. I looked around the site and read the FAQ and I'm not sure if this is the place to post, so if it's in the wrong place, feel free to edit/move it.

I've been talking to a seller on eBay about this item:

http://www.ebay.com/itm/Jake-Arrieta...wAAOSwLnlWmpAi

As a huge Cubs fan, this ball would be wonderful to add to my collection but the seller and I have both admitted to not really being able to come up with a fair price. On one hand, unsigned game used balls from that same game are going for $200 - $250 or so and balls signed by Arrieta usually go for $75 - $100. Then again, none of the other game used balls on eBay are pitches actually thrown by Arrieta, so this one is a bit more unique.

Has anyone ever bought something similar to this that can help me gauge a fair price? It's really tough to find any kind of comps. Thanks for any help you can give! This website is fantastic!

I'd put it pretty close to this one that went unsold at $400, at $1500 that guy is nuts!

http://www.ebay.com/itm/Clayton-Kers...p2047675.l2557