E-Commerce Plugins HELP please!

Hello! This place has always been so helpful for me. So I keep coming back.

I have a question regarding e-commerce plugins for wordpress. As far as I can tell (and can only get to work on), they seem to only work on ”blog posts”. I have themes that use ”portfolio posts” that i would like to add e-commerce functionality to, but none of the e-commerce plugins will kick in on a portfolio item. Is there a workaround for this?

I am hoping someone is able to offer up advice on how to get them to work. I have not decided on an e-commerce solution as of yet, so, feel free to offer up advice on the best one for what I would like to do.

Thanks everyone!

~ND