ChrisHurst

MyWebsiteAdvisor

Allows for Free Checkout with WordPress e-Commerce Plugin. 
Can be used with 100% discount coupons and $0.00 products. 
When the cart total is $0.00 the payment form will be replaced with the text ‘Free Checkout’ and offsite checkout will be skipped.
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Support: http://MyWebsiteAdvisor.com/support/
Plugin Page: http://mywebsiteadvisor.com/tools/wordpress-plugins/wp-e-commerce-free-checkout/
<a href="http://mywebsiteadvisor.com/tools/wordpress-plugins/wp-e-commerce-free-checkout/" rel="nofollow ugc">Premium Version with Advanced Features</a> including:
<ul>
<li>Available To Members Only Option.</li>
<li>Available Only To Specified User Roles Option.</li>
<li>Hide Billing And Shipping Address Forms.</li>
<li>Customize the ‘Free Checkout’ Message on the Checkout Page.</li>
<li>Lifetime Priority Support and Updates!</li>
</ul>
Learn More Here: http://mywebsiteadvisor.com/tools/wordpress-plugins/wp-e-commerce-free-checkout/
Requirements:
<ul>
<li>WordPress</li>
<li>WP e-Commerce Plugin</li>
</ul>
To-do:

Name: WP e-Commerce Free Checkout

Allows for Free Checkout with WordPress e-Commerce Plugin.

Fahad Mahmood

Invoicepress

<ul>
<li>Author: <a href="https://www.androidbubbles.com/contact" rel="nofollow ugc">Fahad Mahmood</a></li>
<li>Project URI: <a href="http://androidbubble.com/blog/wordpress/plugins/wp-quick-shop" rel="nofollow ugc">http://androidbubble.com/blog/wordpress/plugins/wp-quick-shop</a></li>
<li>Free Version: <a href="http://demo.androidbubble.com/wp-quick-shop" rel="nofollow ugc">http://demo.androidbubble.com/wp-quick-shop</a></li>
<li>Premium Version: <a href="http://demo.ibulb.work/wp-quick-shop" rel="nofollow ugc">http://demo.ibulb.work/wp-quick-shop</a></li>
<li>License: GPL 3. See License below for copyright jots and titles.</li>
</ul>
WP Quick Shop is a WooCommerce compatible plugin which enables you to setup a one-page shop for items to sell in bulk. You can add notes for each order item with custom field. WP Quick Shop can be implemented with just a shortcode. Create a page and paste shortcode. On Quick Shop page you can set quantity of items and use add to cart feature instantly. Every item is provided with a button to buy that item individually. Custom field will be saved with order details. Select Custom Field tab and enabled it. You can set custom field type like textarea, text and number. Column heading, field placeholder, tooltip and max length of field can be managed as well. Some styles are available for free and you can add your custom styles as well. Bootstrap is a premium feature as it will involve some complications with your theme templates and you might will require support from us later.
Quick Implementation: 
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/Jft94_xHrvU?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
Important!
Visit my blog and suggest good features which you want to see in this plugin.
<h3>License</h3>
This WordPress Plugin is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or any later version. This free software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this software. If not, see http://www.gnu.org/licenses/gpl-2.0.html.

WP Quick Shop

WooCommerce & WP eCommerce compatibility offered in initial version. Soon more plugins will be tested and will be offered in compatibility list in addition with new features.

Multiple shopping cart plugins can be used together

WP Quick Shop is a great plugin to order multiple products together without searching and spending time on pagination.

Name: WP e-Commerce Free Checkout vs WP Quick Shop