ATM you can buy Twist Drill Bit for 8.04 USD (in Banggood). Go down and check coupons out. Remember to check price history if it is available. What is best price?
Latest price update (UTC time):
Banggood (8.04 USD)
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood. Isn’t it too expensive? Well, this price is higher than average price (6.63 USD)
Link: Banggood product page
Price: 8.04 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG589b2e, BG20236Tool
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Aliexpress
Click here… to search for 60Pcs 1/1.5/2/2.5/3/3.5mm HSS Twist Drill Bit Set on Aliexpress
Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for 60Pcs 1/1.5/2/2.5/3/3.5mm HSS Twist Drill Bit Set is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).