If you can properly diagnose the issue and have the tools and ability to fix it, then I would say save some money and do it yourself. If not, in your effort to avoid getting "ripped off", you run the chance of just throwing parts at the vehicle hoping the next part will fix it, spend all the time doing this, and possibly cause more damage to the vehicle in the process, and compared to taking it to a mechanic, you might end up spending a lot more money and a lot more time.
I will never begrudge a mechanic from making a living working on my car. They have overhead in the building that they need to pay for and they, just like you, want to take a paycheck home at the end of the week. Are there some out there that don't operate on the up and up? Absolutely. However, I would say that the majority of the folks in that field want to do a good job for a fair price.
I do most of my own work so I can save some money, not so I don't get ripped off by a mechanic. In all my years, I can honestly say that I never felt ripped off or deceived by a mechanic that I selected to work on my vehicles. I do, however, spend some time to make sure that I can trust them. I may not have liked the amount at the bottom of the receipt, but that was more motivation for me to learn more stuff.