My understanding is that if you switch on sales price lists then Odoo will always try to get the price from a price list, and if it can't find a price then it sets the price to zero.

The problem is that if you manually enter a price on a sales order line, editing that line (e.g. changing the order quantity) causes the price to get reset (to zero if you haven't set a price on a price list).

This seems to make it impossible to use price lists selectively - either you use them everywhere or you don't use them at all.  

Does anyone have any suggestions on how to overcome this limitation?