The ones that work best are called Pro-Ana. You can get the paper versions or $1. These ones still work fine, they are just not durable.
https://www.3dstereo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GLA-CRC-B-PA https://www.3dstereo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GLA-PROA
The BIAL glasses are also very good and easier to get on Amazon, for $10; https://www.amazon.com/BIAL-Red-Blue-Glasses-Anaglyph-Game-Extra/dp/B01ANJXCU2/