Just check coupons out (with price alert and history). Best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
| Image | Product (link) | Price | Coupons |
|---|---|---|---|
 |
Silicone Earbuds Ear Tips Non-slip Replacement Earplugs for Sennheiser Momentum cx3.00 cx5.00 CX7.00BT In-ear Earphone Earplugs | $9.77 | – |
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Package Contents: 1x Pair of Earphones, 3x Pair of Eartips
Price history and price alert
Do you need price history chart (for all/most countries) for Sennheiser CX3.00 Earphones? There we go.
Price records source(s): Gearbest
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).