Well you should start with a price then see if there is any interest, the after 24 hours if there has not been that much demand (people asking for lower price etc) then you can do a price drop, with a price drop bump (£340 for example). Can do as many price drops as you like after 24hours to the previous one.
If you don't want to go lower than a stated price do a price drop and say you won't be willing to go any lower.
People do make offers, lots of time they are met in the middle if they are not stupidly low.