Reddit mentions of uxcell 10 Pcs Plastic PCB Mount 5-Pin Stereo 3.5mm Socket Audio Connector

Sure thing! I used a Teensy 2.0 with this code: github link. More info on using the teensy as a joystick can be found here. My code should be commented for clarity, but let me know if something doesn't make sense.

Most of the main parts came from adafruit.com or Amazon:

• Raspberry Pi 2
  
• 5 inch HDMI screen
  
• Power/recharging circuit
  
• 6600 mAh Li ion battery
  
• Audio amplifier circuit/volume control
  
• Headphone jack
  
• Tact switches for bottom buttons
  
• PCB for bottom buttons
  
• Power switch
  
• 0.5mm pitch FFC/FPC connector
  
• 0.5mm pitch adapter board
  
  Assorted wires and cables came from Amazon or adafruit, make sure to find ones that are very very thin.
  
  Using the original WiiU buttons was a nightmare. I do not recommend using the original button assemblies unless you are confident in your soldering abilities. Scrapping the original assemblies will also provide a ton of extra interior space. Connecting the 0.5mm pitch flex cable was awful, I was constantly afraid that I was going to burn through or rip something. I did actually over-solder one of the pin connectors and spent about 30 min with an iron and a needle trying to re-separate the pins. If I did this again, I would mount tact switches to a PCB and attach that to the front face of the controller. That would also save a ton of space on the inside and wouldn't require code modification.
  
  Adafruit's Super Game Pi tutorial was also a good reference for wiring the power and audio components.
  
  I'm happy that I could help you out with your project. Good luck and let us know how it goes!

off the top of my head around 120-150 but thats assuming you buy everything online with free shipping and assuming you have access to alot of tools.

Pi Zero https://www.adafruit.com/product/2885 $5.00
LCD https://www.amazon.com/BW-3-5-Inch-Monitor-Automobile/dp/B0045IIZKU/ $15.50
USB Sound Card https://www.amazon.com/Sabrent-External-Adapter-Windows-AU-MMSA/dp/B00IRVQ0F8/ $6
USB HUB https://www.amazon.com/Adapter-Converter-Android-Samsung-Transformer/dp/B00OZDUTMM $6
Volume Potentiometer https://www.amazon.com/16x2mm-Double-Taper-Duplex-Potentiometer/dp/B00O9Y6Z70 $6
Mono 2.5w amp https://www.adafruit.com/products/2130 $3
ABXY PCB http://store.kitsch-bent.com/product/common-ground-dmg-button-pcb-a-b-x-y-version $11.75
Power Boost 1000C https://www.adafruit.com/products/2465 $20

Female micro usb https://www.adafruit.com/products/1829 $1
female usb socket https://www.amazon.com/uxcell-Female-Degree-Socket-Connector/dp/B00FH85SGG Free or $6
Stereo Jack https://www.amazon.com/uxcell-Plastic-Stereo-Socket-Connector/dp/B00GLQAF7A $6
Slide switch https://www.amazon.com/uxcell-SS12F32-G7-Position-Switch-Solder/dp/B007QAJWYW $6
Membrane set http://store.kitsch-bent.com/product/silicone-buttons $2.75
Extra button set http://store.kitsch-bent.com/product/custom-buttons $2
28mm Speaker https://www.amazon.com/Metal-Inside-Magnet-Player-Speaker/dp/B00O9YG9GM $6.50
two single button pcb http://store.kitsch-bent.com/product/easy_buttons $4.30
2300mah Battery http://www.microcenter.com/product/458057/2,300_mAh_Li-Po_Battery_and_Charger $15.00