There's a guy that services the Jewish community in SD and crosses them to TIJ and viceversa with people visiting from MEX. It's great service he'll pick you up where you tell him to and he'll drop you off at the airport. He's got SENTRI, he's got child seats if you need them as well. Only downside is that he uses an older van, but seeing how you would end up in a Tijuana taxi anyways it's not really relevant.
He charged me IIRC $70 he picked me up at TIJ and dropped me off at the Alamo near SAN, on my way back he was already waiting for me at Alamo when I got there and dropped me off at TIJ. I'll PM you his contact details if you want me to.
I used to do the taxi shuffle as well but there's just nothing as convenient and comfortable as having someone pick you up and drop you off exactly where you ask him to.