Lief's ECG stickers can be bought directly from the Lief mobile app (Menu>Store) for $19.99 for a pack of 15 pairs + shipping costs. Shipping cost varies by country, but ranges between $20-$25, typically.

You can wear each sticker pair for 2-5 days at a time, so that should help you calculate how often you'd need to replace the sticker packs. The Lief stickers are particularly suitable for sensitive skin.

Alternatively, Lief’s ECG sticker's snap mechanism is a standard size, so you can search for "ECG electrodes" from local vendors if you’d prefer to avoid international shipping costs.