Hi sixdeuces,
You can try this, but works only for amazon:
AMAMPLACE
Another option, and with this you can cover all the others websites is to buy Hikashop Essential or Business, where you can create custom fields for your products.
Just go to: Hikashop > Display > Custom fields and create a product custom field of type link, Label: Amazon, column name: amazon_url.
In Display section set to yes: Front-end and Back-end Form and save it.
You cand do the same for the rest of website's you use, RedBubble, ebay..
After that, when you will add or edit a product, you will have the custom filds on the product page.