CommerceBird

Using this plugin you can reduce the prices of the WooCommerce products by given percentage+100%. 
If the standard tax rate is 21% in your store, enter ‘121’ in the percentage field and click on update. All your product prices* will be reduced with 21%.
**Important: please read how it works first. There is no second chance in changing prices
<h3>Q: Can I revert my prices update?</h3>
A: No, so please make sure you enter the correct percentage + 100

WooCommerce Update All Prices to Excl VAT

Using this plugin you can reduce the prices of the WooCommerce products by given percentage+100%.

CurtisL

PriceWaiter

mthnz

mattbain

Why PriceWaiter?
PriceWaiter® lets customers make offers on products you sell — offers you can accept, reject or counter. The widget embeds a configurable Name Your Price -or- Make an Offer button on product pages in your WooCommerce storefront. Simply install the plugin and you’ll have full control over PriceWaiter in your WooCommerce admin panel.
<ul>
<li>Engage more visitors</li>
<li>Convert comparision shoppers</li>
<li>Make M.A.P. moot</li>
<li>Increase conversion rates</li>
<li>Sell more</li>
</ul>
For more information visit our <a href="https://www.pricewaiter.com/integrations/woocommerce/?utm_source=wp-plugins&utm_medium=website&utm_campaign=integration" rel="nofollow ugc">WooCommerce Integration Page</a> or <a href="https://docs.pricewaiter.com/platforms/woocommerce.html?utm_source=wp-plugins&utm_medium=website&utm_campaign=integration" rel="nofollow ugc">WooCommerce Docs Page</a>.
<h3>Product Cost Field</h3>
PriceWaiter adds a <code>Cost of Good</code> field to all of your products. This should be what the product costs you. 
We recommend you complete these fields so that PriceWaiter will be able to make accurate decisions if you choose to enable our Advanced “Automation” mode.
If you are already using the <a href="http://www.woothemes.com/products/woocommerce-cost-of-goods/" rel="nofollow ugc">WooCommerce – Cost of Goods plugin</a>, that’s fine our plugin works with it.

PriceWaiter for WooCommerce

This plugin integrates PriceWaiter's powerful price negotiation and conversion tools with your WooCommerce store.

WooCommerce Update All Prices to Excl VAT vs PriceWaiter for WooCommerce