I would say it all depends on how much you will spend on a bike, how many miles (hours) you will be seated on your longest ride and level of fitness also enters into it. If you will be spending what you consider to be a good sum on money and hope to ride longer distances, it is likely a fitting will be worth while but the initial fitting need not be too elaborate. I say this because after some miles under your belt as as cycling fitness improves, the initial fitting will probably no longer be valid. After an initial fitting, as a newby you would new the fit modified. I would try to negotiate an arrangement where you could go back after, say, 6 months for mods.