I need a website plugin that will allow customers to design and order banners and yard signs online.

Our sign company has a full service graphics department, we are looking to add a plugin to our website that will allow visitors to design and order banners, yard signs and similar items without the need to interact directly with our staff. If you know where we can obtain a plugin for this purpose please let us know. Thank You !!!

I doubt there is a plugin like you describe - it would almost certainly be a customised script that you would be looking for. Perhaps others can make suggestions that help you.

It’s too specific for a stock marketplace

There are product customisers on codecanyon but more for T-shirt’s etc and it would be easier to build something from scratch than try to modify these for what you are after

If you have a sensible budget then have a look on www.studio.envato.com