These are standard O-ring sizes, I purchased them on amazon or ebay which ever is cheapest.
I just ordered #135 to see if that the winning one for the top
Silicone o-rings Size 135 Price for 10 pcs | eBay
Silicone Rubber Orings. Silicone rubber has a wide temperature range which makes it useful in many applications. Temperature range: -103°F to 446°F (-73° 260°C). Excellent resistance to compression set, good electrical properties, good resistance to...
Here is a good list of them for sizes…etc, AS568 O-Ring Size Chart | Standard USA O-Ring Sizes