Licensing my CMS commercially, without having to use a solicitor

Hey, I've been looking at distributing my CMS by selling copies of it on the website. I have been working hard on it for two years and don't plan to just give it away for free like a lot of open source CMSs out there. However, I want developers to have access to the code so they can make the alterations they need to make, and also submit bug reports etc. What I don't want though is for them to change the code a bit and then re-release it as free, or even sell their own version of it. I've looked at GPL but there are issues when selling software under GPL. The closest license that I have found is the ExpressionEngine license, but then to get something like that I'd have to pay a solicitor a lot of money to draft me a license and I just cannot afford it. The CMS is Halogy - http://halogy.com and is at the moment hosted. I get emails almost daily asking when its going to be released or sold, and I can't really answer the question until I have the right license for it. What I do know though is that I want to release a free copy for Non-Commercial use, a 'Freelance version' for about $99 and a commercial version with lots of modules for about $199. I would also like to sell modules separately in a shop. Please advise. Thanks guys.