I nuked the amazon gift card I got for Christmas and ordered a hydrometer from Fisher Scientific via Amazon.
It's marked in specific gravity only, so some light math is needed to convert to baume/brix. And its range is wide enough that it will handle anything usually occuring in the kitchen. Prior to this, I'd been using a erstaz approach, and using a brix syrup (# grams sugar per 100g water= deg brix). I'd have to WAG when adding it to purees and juices for sorbet.
I also picked up a graduated cylinder as a testing vessel.
I think it was a pretty good deal for ~30 bucks total. Well worth it for conistent sorbets.