Taxes on importing those hardware are inevitable since tariffs are always assessed on goods entering every country specially if the price of it is quite high. Income taxes from bitcoin mining operation is quite hard to compute. I don't think there are already countries who gave the exact formula on how to compute taxes from it. Things that should be considered are, the expense that you had for mining the coin. Where are they going to base the income that you got from mining since the transactions are somehow anonymous how can they get a record of the exact number of coins that was mined by the farm.