Firstly, why do you want an e-file? if you think it will make your service quicker, it doesn't I have spinal problems which mean I can no longer hand file and the e-file does the debulk in a re balance. It takes me 1 hour 15mins to 1 hour 30 to do a full set and about 1 hour 30 to rebalance.
This is the same as when I hand filed.
What I learned and what brought my time down was to not put the product on in the first place. Full set or rebalance all I do now is buff over, shape and shine, why put it on just to file it of?
All of that said if you are determined to buy an e-file don't get it from ebay, you have no idea what makes a good file or a bad one so you won't know if what you are buying is what you need and they are not cheap so you need to make sure you get it right.
NSI do efile course with local trainers so if you call their head office they will put you in contact with an educator in your area,
Young nails also teach e-file classes, but I don't know where their training takes place.