Hi Ozpoker,
VirtueMart has this feature already built in. It is known as Related products in Virtuemart. To set this up go to the product list in VMs control panel and click on a product. From the Product Information page click on Related Products, you should be able to set this up from this page.
If a shopper click on a product you have set a related product for, they get the message “You may also be interested in this/these product(s)”. You can change this to say “Customers who bought this product also bough this…” if you want. To change the wording locate
yoursite/Administrator/Components/Com_Virtuemart/Languages/Common/english.php
Scroll down to about line 523 ‘PHPSHOP_RELATED_PRODUCTS_HEADING’ => ‘You may also be interested in this/these product(s)’,
Have fun and don’t forget MJs rule number two backup backup backup backup