Why use a complex component like Virtuemart if you're not actually going to use most of it? Virtuemart (and similar extensions) process the payments through a payment system like PayPal, Stripe, Google Wallet, Amazon etc using an API. Just communicate directly with the API from your component.
Many of these systems includes a shopping cart that can be easily integrated with your website:
PayPal is a popular option, supporting both payments from other PayPal accounts, and direct payments using credit card. A shopping cart can also be set up if you want your customers to be able to add several products and pay everything at once. Security is handled by PayPal.
<button type="button" class="snipcart-add-item"
Add to cart
There are many other options, but these are the ones I've used myself.
The major advantage of this approach is that you add all the code inside your component, without requiring the user to install (and configure) a third party component for your system to work.