I had a paid fit at one point, but it was because I was having pain and could not figure out the cause myself after trying all the basic stuff mentioned online. If the pain you are in > than your need for the $, do it. A repetitive injury will end up costing you more down the road in time off the bike and/or PT. There's a difference between niggling little discomforts (which often go away with additional exercise) and actual pain from repeating a movement with a bad fit.
Try to figure it out yourself if you can. If you can't, then a fit may be necessary.