fuel injector service
 

Recently, I went for an oil change for my 2000 mazda millenia (52,000) miles.
The guy recommendeda fuel injection cleaning ($126). Can you provide any recommendation regarding this kind of service. I'm not a car guy, and I don't want to get taken. The service tech said that the fuel injector bottles you buy at car stores won't do the job.

Also, he is recommending me to change my steering wheel fluid. Is this something I can do myself, or is itas complicated as he says. That two tubes need to be connected. One to suck out the existing fluid and another to run the new fluid inside. Cost $89.
I need advice on what to do and where to go. Please be specific. Thanks.