yeah oil changes are one thing I usually wouldn't bother to do myself. I can't get it done meaningfully cheaper by myself, as my costs are the same as you - $50 for oil + filter. at least disposal is free for me (hazardous waste dropoffs hosted by the city / tax dollars).
however I did start doing them myself to avoid having to spend time getting to/from the shop, if I needed a change and my car wasn't going to the shop for another reason sometime soon.