Suppose the installment interest rate of the bank is 0.6%, and the total interest of 12 installment is 50000 times 0.6% times 12, which is equal to 3600 yuan. So if we choose installment 12, the total cost should be 50,000 yuan plus 3,600 yuan interest, which is 53,600 yuan.

Note that the installment interest rates of different banks will be different. It's best to consult the issuing bank for specific fees, and they will give accurate values according to their own banking policies.