Looking for a server to dev for

Hello all of PMC!
I have been in the minecraft server business for about 3 months and have been growing sufficiently. I have had experience in configuring and JAVA coding for around 6 months and have been wanting to put that to not just the use of my server, but to the use of other servers. I will make custom plugins at a minimum price of about $5 for small projects. Helping and fixing configs, though, is a free service! Please reply to this so we can talk about what you would need!
Thank you all!