Websorcery

This plugin automatically hides the “Add to Cart” button for WooCommerce products that have no price set (or empty price). Instead, it displays a customizable “Request Price” button that opens a lead capture modal.
Features: 
* Automatic detection of checking empty prices. 
* Lead capture form (Name, Phone). 
* Email notifications. 
* Customizable design via settings. 
* GDPR compliant checkbox. 
* Localization support (i18n).

Websorcery Request Price

Replaces "Add to Cart" with "Request Price" button for lead generation.

Denra.com

Ivaylo Tinchev

There are some products or services that cannot be sold directly via shopping cart. This plugin allows your prospective customers to easily request a quotation from you using a simple and easy to use contact form.
It takes lots of efforts to develop and support a plugin. Please send us your feedback and questions to fix your issue before leaving a bad review.
Are you satisfied by using this plugin? Consider leaving a <a href="https://wordpress.org/support/plugin/really-simple-rfq-form-for-woocommerce/reviews/?rate=5#new-post" rel="ugc">5 star review</a>.
If you need support or more information about this free plugin please read the description and the F.A.Q. section below or write in the <a href="https://wordpress.org/support/plugin/really-simple-rfq-form-for-woocommerce/" rel="ugc">Support Forum</a>.
<h3>Features</h3>
<ul>
<li>Simple and easy to use RfQ form with name, email, phone, questions or comments fields.</li>
<li>Uses AJAX submission and the user does not leave the page while sending the request.</li>
<li>Automatically adds the product name, SKU, picture and link in the request message.</li>
<li>Emails the requests using the built-in wp_mail() WordPress function.</li>
<li>No complicated settings. All is setup to go. Simply install it and it works.</li>
</ul>

Really Simple RfQ Form for WooCommerce

Removes the 'Add to cart' button from WooCommerce and adds a simple 'Request for quotation' form on all product pages.

Websorcery Request Price vs Really Simple RfQ Form for WooCommerce