That seems like an obvious choice to me: live near work.
Driving 90 miles round trip each workday will result in over 20,000 miles of extra driving a year. Even with conservative assumptions for the cost of driving, this will eat up the savings of the cheaper rent (in reality it may very well cost you more).
And that's without factoring the value of your time, and the health value of biking 8 miles a day. Assuming it took you half an hour to bike to work, it sounds like you would gain an hour of free time each workday, which is nearly 10 days of time each year.