Planning out my next machine build and I'm hoping to get some advice on the spindle. I plan to drive a bt30 cartridge with a dmm 1.8kw servo. There's quite a few options for cartridges on aliexpress for decent price. They come ready to go with spring washers, petal clamp, etc. Price goes up relative to max rpm they can handle, which I assume is mostly a difference in bearing quality and balancing. Anywhere from 5k max to 14k max. Price from a few hundred to 1500. Since I will be working in mostly aluminum with smallish parts, I want all the rpm I can get. When I started searching for a spindle, 12k was the fastest available with a price of 1250. I contacted the seller and said "12k will be good, but do you have anything faster? Like 14k?" His response makes me a bit nervous. He said "sure, here is a 14k max spindle". He also provided a link that took me to a listing that looks identical to his 12k rpm max spindle. Only difference being that the max rpm spec was 14k and the price was 130 bucks higher. This listing did not come up previously when I was searching. It makes me a bit doubtful that his "14k max spindle" is any different than his 12k spindle and hes just telling me what i want to hear to get a sale. Maybe I'm being paranoid.

Does anyone else have experience with one of these bt30 spindles from aliexpress? I'm obviously not expecting top notch stuff for that kind of money, but I would at least hope it should perform as advertised for a couple thousand hours or so.