Nothing is better than a correctly calibrated refractometer. You can calibrate it with RO water or they do sell calibration fluid.
I would suggest spending your money on this nice piece of equipment now instead of later. SW aquariums are a big investment, not worth a silly error like a bad reading on salinity.
That being said, I know many many people who still have the plastic swing arms and live by them. More of a personal choice I guess.