Originally Posted by CCM Photographer
The camera has flash but I'm not using it. I have lights on opposite ends of the box that pass through translucent cloth. Elmer's Foam Core Board
is what I use for the box along with some white wrapping paper for the background.
Cheapest method for you would to be keep using the setup you have light wise, and if you are not already, buy or start using a tripod for your camera ( thus alleviating any movement and blurry shots), and just buy bigger sheets of whiteboard and t build a bigger box and start using longer shutter speeds to overexpose the background. Looks like you are doing a fine job already and you stated you are using PS to some extent anyway to refine your the image background.
Also, if you are wanting some help refining your light setup and are not too proud, you could always post a raw image before you doing any post production so we can better see what kinda results you are getting straight out of camera. Just a thought. I'd be happy to help you further if you need to. Just post back here or if you want to feel free to PM me.