Create Html Editor for my joomla site

I do alot of ebay store designs and would like a way for my customers to upload the code I give them for their template to a html editor on my site that gives them a preview of what their design looks like to make changes to it - most important is a image button that will input a URL where the image field would be. I know there are freebies out there, but I want one thats easy to use and just has a editor and the image URL replacer.