I want to list my products but without the price, so the buyer calls us to purchase

You need to have a price for a product for it to appear online, but if you add a nominal surcharge (like 0.01) using a variant template, the product will appear online even if the actual price is 0. Make sure the stock of the product is set to 0 so that they will not have the chance to add this product to their basket since the price will be $0,01 when added.

You can then add a description to the product page saying "Please call us to purchase".