Aftermarket seals vs. OEM?

It's hard to make the call on specific parts because sometimes, even cheap stuff works out ok. You'd need to look at the all parts (perhaps in a category such as seals) and figure the total reliability and then make the call on where your risk threshold is. For example, I buy cheap hand tools from Harbor Freight because a) it's cheap and easy to replace them if they fail, and b) they actually don't seem to fail very much, but I'm sure some categories of items at HF are junk. I bought a tire pressure gauge / inflator from HF and it leaks around the valve stem so I'm unable to get a good reading. It cost ten dollars so I'm not overwrought about it, but I'll likely buy the next one from somewhere better.
If you don't mind the risk of extra labor, you could install the ebay ones. If I were in your shoes, I'd probably install the Cat seals or at minimum the ebay seals because I have less time than money (and I don't have much money..) so avoiding a few extra hours of work is worth more to me than the 370 dollar difference. Just some thoughts.

I guess we might be kind of opposite lol. I would rather spend more time on something as opposed to money. I guess because for me, all my equipment is for hobby purposes only, not to make money with. Also, I enjoy the work.

As far as tools, I never buy anything from China if I can avoid it (Harbor Freight, Home Depot, Lowes, Tractor Supply, Runnings etc) I usually buy Proto brand hand tools online these days. Only exception is very large size wrenches/sockets that are not used all that much and kind of impossible to break due to their bulk.

The main reason I hesitate to buy the Chinese seals/parts is for political reasons. I do not like supporting the Chinese economy.

I don't have to reseal the stick cylinder as that was done by a dealer about ~300 hrs ago. I paid over $800 to have them reseal. I'd rather not do that again. The only issue I don't have a solution for if I reseal myself is the ~2600 ft-lb required for the piston nut removal/replace. I'd have to make some kind of workbench and acquire a torque multiplier capable of ~3200 ft-lbs.

Unless you are getting NOS USA seals current production is most likely foreign anyway. About all you can hope for is maybe the Brand Names might have better control of quality.

Anyone know how I find/purchase Cat Publication PEXP1020? I am told it is a seal kit catalog??? Looking for seal kits for my 225 51U vs. purchasing individual seals...