I'd recommend you to check your market's needs, meet buyers, get in touch with people interested in buying machines and see what they need and/or want.
Also, offering them different miners (in stock) and with pre-order might attract more people to buy from you.
Also, where are you from if I may know?
im from Spain and i thought that people from the us dont pay tariffs for shippings from europe but if its not that way at least people from europe can buy me tariff free
favebook i thought preorders were worse because mining gear market is full of scams and even having miners in stock i assume is going to be hard to get a good reputation