Hi Pist0lpete,
There are some search suggestions in the help section here which may be helpful 
As you probably know I think very highly of Jim and Oklahoma mattress and they are a member of this site which means that I believe they compete well with the best in the industry and since they are local to you I would certainly include them in your research although you would need to call them to confirm they make crib mattresses.
Post #2 here also includes links to the better forum posts and topics about mattresses and children and outside of the topic that Dubious linked (thanks Dubious :)) some of the other topics that discuss crib mattresses include this topic and this topic.
The key factors about a crib mattress are a suitable size (no gaps between the mattress and the crib), using “safe” materials, and a very firm and resilient sleeping surface (firmer than would be suitable for an older child or an adult) so that there is little “give” for them to sink into (which can create a safety hazard) and that will provide good support when they sleep, move, or start to stand up.
The members of this site that sell crib mattresses online that I’m aware of include …
http://www.rockymountainmattress.com/
Calgary, Edmonton & Sherwood Park Mattress Stores | Mattress & Sleep Co. (Canada)
Phoenix