If you use devices from another country on clients, firstly you won't get insured on it easily as you will need training from the manufacturer and the insurance people will require information from the company sometimes. Secondly the devices sold on ebay although they are cheap the components within the devices are rubbish, i've seen so called salon equipment for £30 - £50 which i'm guessing would break within a couple of weeks or months. we met a lady who bought an LED therapy device from online once and she spoke to us at one of the trade shows, said she got it really cheap but after the second use her skin became red raw, turns out the mask was heating up (which she thought was normal) and the 'led' lights were actually the types of lights like a bulb which heats up. if she'd have used that on a client she'd be in real trouble!
if you're using it on yourself you can risk it but with clients you have to be careful saving a few pounds here and there might cost you dearly.
Some British company devices are made in china due to low labour costs etc but the components will either be from Britain or Germany and UK based companies selling these devices have to be registered and insured themselves to sell the products. So as a therapist if anything goes wrong with a device you know you have the backing of a company to help you out.
I personally think diamond is better than crystal and i can send a pdf of the comparisons to anyone interested in finding out the difference, just message me. Diamond tip devices were actually brought out because of the problems with crystal dermabrasion, but sometimes its just a case of trying both or researching both and finding out which one you want for your clients or yourself.
Best Wishes,
Mel