The Metrolink has been fairly-improved and more lines are actually being built to service more area. If everything you need to do is near one of their stations, I'd try to find cheaper housing out in an area close to one of those stations (Riverside, San Bernardino, Fontana, Corona, etc.) I lucked out in that my job and home are very close to Metrolink stations, and if I'm on my e-bike I can just use the bike trail in the Santa Ana river and go home/get to work that way. I still drive because it is usually faster (and cheaper) than taking the train, but trains are an option.