The last time I took Lola the Corolla in for an oil change, the mechanic offered to change the air filter for the low low price of $60. (A month before, the Toyota dealership offered to do it for $120). This seemed a wee bit pricey.
Instead, I went to O'Reilly Auto Parts, joked with the guy behind the counter about how "proud" the dealership was of its air filters, and walked out with an air filter that cost $12.99. I drove home, found some instructions online, and popped Lola's hood. Five minutes later, I had replaced the air filter myself.
I saved myself $50 and feel like a total grease monkey. It was totally worth it.
Yours truly (greasy fingers and all),