A few years ago I bought bearings from RC Bearings for my Thunder Tiger 46 Pro airplane engine. No problem what so ever.
Now I race 1/8 nitro buggies and needed new bearings for my practise engine. Will these low cost bearings last in a high end car engine (+34000 RPM)? No prolemos, amigo! :-)
After 20 minutes of idle for break-in of the bearings I hit the track. The engine performes at least as well as it did with the original bearings and I believe, they will last many gallons of fuel.