Three housings for the ispring water filter with o-rings + one extra new filter for middle housing + extra valves: $5
These are stage 1 to 3, clear see through to other two opaque housing, the middle one has a new filter not used.
Please note: these are housings, you would still need the tank and the rest of the connectors to make a system.
Second item in new condition: iSpring Wrench AWR2 2-in-1 Reverse Osmosis Pre-Filter Housing and RO Membrane Canister Wrench: $5