Yes get a refractometer from ebay. Kinda like the one's in the store but without any brand. Plus the only different that I would guess between the cheaper ones and the brand ones is that you might need to calibrate the meter more often. Other than that, its just a piece of prism through a tube so shouldn't have much of a difference :P
Stay away from hydrometer! They are probably the worst piece of equipment made for saltwater :|
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