Revised estimates have put the cost of a proposed police station in Medford at around $20 million, which is about $8 million higher than previous estimates. The city council was presented with a study yesterday that says the station should be designed so that it meets the needs of the department for the next 20 years. Police Chief Tim George told council members that the current station is dysfunctional. Criminals are escorted past employees and witnesses, and lack of space makes it difficult to interview informants.