I built my first CNC router a couple months ago and purchased ball screws, end bearings and linear rails from linearmotionbearings2008.

The first batch I received the screws was bent, the holes in end bearings was machined off center and the holes on the linear rails was drilled off center. The bearings in the ball nuts was incorrect introducing play. I was furious.
Chai was willing to send me replacement parts but he expected me to pay again for the shipping of $150. After weeks of debating I gave in and told him I will pay 50% of the shipping.

He sent me replacement parts. The ball screws was slightly better but still bent and the one ball nut was "wobbling" and once again the linear rails was drilled off center. Not only were they drilled off center, they were bent too.

I'd recommend to anyone who are serious about building a CNC machine to avoid linearmotionberaings2008. He has 100% positive feedback because he will refund you a small amount in return for positive feedback.
I received $50 refund after spending nearly $700. I still left negative feedback but he somehow managed to remove it.

Here are some videos and photos of the parts I received from him:

https://youtu.be/jyXBtSAM9RM
https://youtu.be/CejcBfJLDDc
https://youtu.be/asCSsKSqICA
https://youtu.be/uE-8RjmRM-0
https://youtu.be/HICrYKOXq7o
https://youtu.be/7NtMcUeOHO4
https://youtu.be/t2bIGd0rBSA
https://youtu.be/5Iy8zLk3KQw

For a little more I managed to purchase parts locally which are 100 times better. No bent screws or skew rails.