Quoting Sam H.:" woah how do you get it through your insurance?! that would save me 270 bucks! and what do you mean by a closed system?"
a closed system can be shared because the internal structure is protected so diseases and infection cannot be passed from one person to the other. These are usually hospital grade pumps. Open systems can get stuff in them, so its not advised that they be shared so that infectious diseases cannot be transferred from one person to another.
Call your insurance company and ask if they cover breast pumps. They will tell you their policy and procedure for obtaining one if they cover it.