For meal prepping it is better to invest in metal or glass containers, not plastic. Go to Chang An East road for your pick at the best price.
Plastic freezable bags are OKish from Costco, better quality Korean and Japanese at City Super, PX Mart and Daiso or any Japanese pharmacies in Taiwan. They are a bit thicker than normal sandwich ones. I think those fancy vacuum ones are too complicated, squeeze out as much air as possible and it will be fine.
I reuse them even after storing raw meat in them. Fill them with soap and water and microwave for 30 seconds, or until the blood is thoroughly cooked. Rinse.
I did the math a long time ago. It’s cheaper to buy high-quality ziplock bags and reuse them many times. But if you’re just going to use a single (cheap) bag twice, you might as well use two bags. (From a purely cost point of view)
If you’re looking for them in the grocery store, they’ll be in the kitchen section (at Carrefour, they’re near the pots). They’re called 保鮮袋 if you’re looking for ones made for food or 連鎖袋 if you’re looking for ones made for storing small things (not food).