1 x 3.5mm standard headphone jack
https://www.amazon.com/Nine-3-5mm-Stereo-Panel-Connector/dp/B01C3RFHDC/ref=sr_1_24?ie=UTF8&qid=1498441328&sr=8-24&keywords=3.5mm+jack

1-2 x potentiometers (these small ones are nice for setting the volume of the piezo disc or if you want volume control but don't have enough space in your case for a full sized potentiometer)
https://www.amazon.com/Hilitchi-Multiturn-Trimmer-Potentiometer-Assortment/dp/B0711MB4TL/ref=sr_1_2?ie=UTF8&qid=1498441519&sr=8-2-spons&keywords=potentiometer&psc=1

1 x 5way tactile switch
https://www.amazon.com/gp/product/B00E6QM2F0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

4 x tactile switch
https://www.amazon.com/Eowpower-180PCS-Momentary-Tactile-Assortment/dp/B06X6MQ7Q8/ref=sr_1_1?s=hi&ie=UTF8&qid=1498441667&sr=1-1-spons&keywords=tactile+button&psc=1

1 x tft spi screen with sd card slot
https://www.amazon.com/gp/product/B06XXFWRPB/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

1 x piezo buzzer (passive buzzer; the kind that you have to oscillate yourself)
https://www.amazon.com/Passive-Piezoelectric-Ultra-Thin-Low-Power-Electroacoustic/dp/B072NGNRTK/ref=sr_1_27?s=electronics&ie=UTF8&qid=1498442138&sr=1-27&keywords=piezo+buzzer

1 x 9v battery connector (there is probably a better power option, but 9v is just what I've been using which isn't the best since 9v batteries have pretty low capacity and are pretty expensive)
https://www.amazon.com/IDS-Leather-Housing-Connector-Battery/dp/B06X8YZJ64/ref=sr_1_2?s=electronics&ie=UTF8&qid=1498442198&sr=1-2&keywords=9+volt+battery+connectors

1 x on off rocker switch
https://www.amazon.com/FBApayipa-Solder-Rocker-Switch-Toggle/dp/B01N2U8PK0/ref=sr_1_3?ie=UTF8&qid=1498442382&sr=8-3&keywords=on+off+rocker+switch

...also some resistors.