Store products are already marked up via JSON-LD with the Product type which includes the Offer type.
Example:
<script type='application/ld+json'>
{
"@context": "http://schema.org",
"@type": "Product",
"name": "Physical Product",
"description": "",
"category": "Test",
"url": "http://localhost/ips4/store/product/7-physical-product/",
"sku": 7,
"offers": {
"@type": "Offer",
"availability": "http://schema.org/InStock",
"price": "25.00",
"priceCurrency": "USD",
"seller": {
"@type": "Organization",
"name": "Invision Community 4.6"
}
}
}
</script>