You will be obliged to pay for the majority of the DUI expenses only after you were convicted and lost a trial or entered a plea bargain. In case your guilt will be determined, you will need to pay court imposed fees, fines and any other expenses, including probation fees if you are on probation. Besides, you may be obliged to pay for the alcohol and drug awareness classes as well as all the test you submitted yourself to.
Regardless of the case outcome, you will need to pay attorney fees, travelling costs as well as insurance expenses.