Hi,
Yes. When a product doesn't have a price it displays by default the message "free" instead of the price. But you can modify that message to whatever you want with a translation override:
www.hikashop.com/download/languages.html#modify
Then, based on the "display add to cart button for free products" setting, you can have an add to cart button or not for these products.
You can also use the "Display a contact button on the product page" setting to have a contact button on the product page for these products.
Finally, you can use a "collect on delivery" payment method for when the products are free (and rename it request a quotation) and PayPal for when the rpoducts are not free using the restrictions of the payment methods. That way, people can potentially request quotes for a bunch of products at once or pay with PayPal for normal products.