@adrianlu It's about time someone did this. The reality is I think the BOM can be pushed down to $2000 with a little work and some clever sourcing. I will go down the list of items you have highlighted in question and give you my thoughts.
NE555 Pulse Generator Adjustable Frequency Module 5-12V DC - When I asked it's purpose after receiving my kit I was told this "The purpose of the freq generator pulse was to generate a 140khz square wave. After we discovered the arduino had a native function to generate waves within this frequency range the freq driver board became obsolete."
XSPC Ion Pump/reservoir combo - Part of the chiller sub-assembly, holds the liquid that runs through the radiator, see this drawing on the bottom right side.
Mini Air Pump 12v Kpm27h Keurig Coffee Air Purge Pump - I think the main reason they went with this was because it's 12V, otherwise a $5 air pump would work fine.
ATP Vinyl-Flex PVC Food Grade Plastic Tubing, Clear, 1/8" ID x 1/4 - This is for the squirrel fans that make up the "air flush system" you really only need like a foot or two of the tubing though.
PrimoFlex Advanced LRT 0375in.ID x 5/8in.OD Tubing Bundle - Tubing for the chiller assembly.
Standard Airline Tubing - Pretty sure this is for the air pump, you could substitute any other plastic tubing.
1/2" DC12V SS304 Motorized Valve, Electrical Ball Valve CR-02 - For the air flush system, I think the reasoning is that there is no other way to fully seal and create a controlled environment otherwise.
EZO Conductivity Circuit - This is part of the brain assembly, these plug into the top of the OpenAg board.
Rubber washer feet: BS-17 - Feet to keep the chiller from vibrating, surely there has got to be a cheaper solution though.
AFB1212SHE Axial Fan 120x38mm, 152 CFM - Part of the temperature control assembly, it's the fan that circulates the air inside of the growth chamber.
Rivet Nut - These are what go inside of the square framing pieces so that you can attach the exterior panels to them with screws.
Brass Barbed Hose Elbow, 90 Degree Angle, 0375" Hose ID - Fair certain these are for the air flush system and connect to the valves.
Hose Clamp, 17/32" to 39/64" ID - Used for the tubing on chiller, and air-flush system.
Adhesive-Back Strip, Coarse, 1/4" Thick, 3/4" Width - This is either to attach the Mylar to the interior walls, or weather stripping for the door.
Squirrel Cage Blower, 16 CFM - Air flush system.
LLE102000 Liquid Level Sensor - Water manifold sub-assembly. I'm not sure why they went with this type of sensor, perhaps the logic was easier or it is more accurate than a float?
1 Gallon Round Jug with 38/400 Cap - For water top off, this is the big jug pictured on the side of the PFC under nutrients.
Here are some notes about parts you hadn't highlighted but I wanted to point out as well:
FOAM PLANT RAFT - Definitely CNC your own for like $5.
SHURFLO (255-213) 1/2" Twist-On Pipe Strainer - Only needed for the submersible pump which really serves no purpose and isn't even available yet.
G1/4" to 0375" Barb Fitting Black Chrome - Fairly certain this is what screws into the radiator and connects to the chiller tubing.
EX120 Single Fan Radiator - Connects to the chiller, useless without a chiller.
Oasis Horticubes (By the Tray of 104 Horticubes) - Way cheaper.
Multifunction Programmable Relay Timer - We really aren't sure the purpose of this yet, if you can figure it out let us know.
RSP-320-24 24VDC 320W Switching Power Supply - Connects to the chiller, useless without a chiller.
120mm Fan Guard - Connects to the chiller, useless without a chiller.
CFM-A238-13-10 Axial Fan, 120x38mm, 201 CFM - Connects to the chiller, useless without a chiller.
In summary, here's my advice:
- Don't buy any parts for the chiller assembly yet.
- I would encourage you to watch the build video at least twice. The whole assembly isn't really documented in any one place, the PDF's show you sub-assemblies but many parts of the main assembly are only shown in the build video.
- Also, our Fenome PFC build post has a Google drive folder link with pictures of pretty much every part.
That should save you $1000!