Regular Price vs Sale Price vs MSRP

There are three price price fields you can submit to Amazon:

The standard price equals the regular price in WooCommerce

The sale price can be set the same way - by entering a sale price in WooCommerce. Sale prices are supposed to be temporary. Since submitting a feed with a sale price but without sale start and end date would fail, WP-Lister automatically fills in missing sale start and end dates with 2010-01-01 and 2029-12-31.

To show a list price on Amazon, you have to enter it in the MSRP in WooCommerce (Maximum Suggested Retail Price) field. Your list price will be shown as strike though price - similar to the regular price when you enter a sale price. 

If your prices are permanently below the list price, you should not use the a permanent sale price to show that on Amazon but list the normal price as list price and your price as regular price.