Hi,
Okay, now i understand what you want. But it might give you some trouble in some cases, for example, for pricing:
Google wants something like this structure:
<m-eta itemprop="currency" content="USD" />
$<span itemprop="price">119.99</span>
In order to capture the Currency and the Price.
But in Virtuemart, price elements are generated with this PHP line (by Virtuemart, officially):
echo $this->currency->createPriceDiv('salesPrice', '', $this->product->prices);
And in the website, the result becomes:
<div class="PricesalesPrice" style="display : block;">
<span class="PricesalesPrice">$234.00</span>
</div>
but it should have been something like below to implement the price rich snippet;
<div class="PricesalesPrice" style="display : block;">
<span class="PricesalesPrice"><m-eta itemprop="currency" content="USD" />$<span itemprop="price">250.00</span></span>
</div>
You see what i mean? I don't know how you can separate the Dollar sign and 250.00 then add the extra meta line between them (without virtuemart core hack). It obvious it will give you lots of pain. And i can't be sure how to achieve this though, 'cause i have never interested in this topic. But i would never recommend you to do the core hack, because in the future you will need the Virtuemart updates, and once you perform the update your all core changes will be retrieved back to stock, which means you will need to do the same modifications again and again.
If you insist on this (making the core hack to virtuemart) i would suggest you to look at forum.virtuemart.net. It is a tough topic and completely related with Virtuemart Components itself. And look for some 3rd party extension to let you do these things easily. I remember some extensions were available for Virtuemart1.1.9, but i can't be sure if anyone has come up with an 3rd party extension yet to achieve what you are looking in VM2.0.xx.
Did you google it and searched for it already?
I just found this extension:
extensions.virtuemart.net/component/sobi2/?sobi2Task=sobi2Details&catid=12&sobi2Id=828&Itemid=2
and it is non-commercial (free) give it a shot. IT promises to give you what you are looking for.
it says:
"This free VirtueMart extension adds rich data-markup to your shop pages so that search engines like Google, Yahoo, and Bing can display richer item previews in the search results ("Rich Snippets") with information about prices, availability, delivery options, images, etc. This typically increases Click-Through-Rates (CTR) by up to 30 %."
Regards.