It would be very useful to be able to create a new sales order for a customer with a price list by going into their price list and selecting product or products from there.

an alternative would be to create a new sales order from a memorised sales order and be able to select for example, "check prices against customer price list" and adjust accordingly if there has been a change. You could then memorise this as a new sales order. . Currently the price list functionality is very poor and probably why it is not used that much.