From my understanding, open deed of sale is a contract between buyer and seller. If there is no name of the seller on the deed of sale, that is open deed of sale..(from my understanding).
yun buyer po ang blank...just like in my case, i bought a lancer. the seller that i bought the lancer from is already the 2nd owner. but when he bought the car from the 1st owner what they had is an open deed of sale. when i bought the car from him he just handed me the open deed of sale. kung titingnan parang ako ang 2nd owner ng car kasi di na dumaan sa pangalan nya.

the cost of making it notarized will depend kung saan/kanino ka magpapa-notarize. may mga pinagtanungan ako, highest e 1700, lowest e 250. syempre alam mo na kung kanino ako nagpa-notarize.