Thrust bearings don't come that slim. The bearings on spring guides aren't that size either, bearing guides are made in two/three parts that are threaded together, the inside diameter of the thrust bearings on them is nowhere near 11mm. It's more like 6-7mm which IS a size you'll find. However, you won't be able to fit them to your fixed spring guides. If you have a bearing on the back of your piston head then you don't need one on your spring guide anyway.
Personally I wouldn't trust any bearing that you can buy from AliExpress for a few pence anyway! This is most likely the sort of price you'd be looking at for something half decent https://simplybearings.co.uk/shop/p504954/F8-16G-Budget-Single-Thrust-Ball-Bearing-with-Grooved-Washers-8x16x5mm/product_info.html