Community edition 5.1.0 is the version on which EAP 5.x is based. So that's the closest community edition you'll get for EAP5.
An earlier post asked about the trial period for JBoss EAP and what happens when the trial period expires. The response from someone on the JBoss team was that the poster could continue to use EAP, it would just be that the poster could not get support. Therefore, your developers could download the EAP trial and use that to do development work without having to do purchase support.
(If I find that post, I'll attach the link) Found it: http://community.jboss.org/message/596271#596271