Where to buy linear rails & ball screws

I've read bstmotion are a good supplier. Here is one of their linear rails:
https://www.aliexpress.com/store/pro...369798368.html

That comes to $230 + $160 shipping + VAT = around £360 for 4 carriages & 2 rails

Now, I also see big kits like this on eBay:
https://www.ebay.co.uk/itm/EU-20mm-S...2/163650557166

That comes to £320 + £32 shipping = around £350 for 12 carriages, 6 rails, 3 ball screws, and a bunch of Ballscrew bearings and mounts. It says stock in the EU so hopefully no VAT and a quicker lead-time.

Am I missing something? It seems I am essentially comparing Chinese components against other Chinese components. The price differences between these two are so huge it is hard to imagine what sort of quality differences could justify it.

The big kit doesn't quite have all the sizes I need, but for the price difference I could easily buy 2 different kits and make up the parts I need then put the leftovers on eBay!!

I'd love to hear about any relevant experiences.

First thing I'd say is not to use BST Motion's Aliexpress store as an indicator, email directly with what you want and they'll quote a package price with shipping. That shipping figure is more than I paid from Fred with a much bigger order.

BK12 and BF12 bearings are just a size specification I believe - it doesn't really tell you about the quality of the bearing. Typical cheaper ones have badly matched bearings with incorrect preload, and often the fixed side has excessive play. Be prepared to dismantle and shim the unit yourself if needed. The problem with all this? Backlash:

https://www.youtube.com/watch?v=3aYmsXQegZQ

There are certainly quality differences between different suppliers - a number of people here have received 'counterfeit' HWIN rails and carriages - what the disadvantages of those are you'll have to ask them, may well be worth the price saving.

Lastly, just because they say EU, eBay sellers regularly lie about their location - they're still quoting up to 2.5 weeks delivery, and one part on the listing claims Prague, the other part claims Germany.

Freds email ** bstlinear***@***gmail.com*** take out the stars