here are som3 links:

http://www.nextag.com/baseball-diaper-bag/search-html

http://www.brandnewdad.com/shopping/diaperbags/messengerdiaperbags.asp

http://search.ebay.com/search/search.dll?from=R40&satitle=baseball+diaper+bag

Check out this website. I have an oi oi bag and love it. The fabric is great and waterproof!! spillss just wipe away…I got a messenger style bag and I think it was $150.
http://www.oioi.com.au/index.htm
Also, coacn and kate spade have nice diaper bags, but they are in the 300+ range. I think you will really like some of the oi oi bags.
Good luck!