Well, there's a lot of us here, so the beer we're making can't be THAT bad!
Seriously, though--store-bought GF beer is terrible compared to what you can make at home. It's like most brewers aren't even trying, really! There are so many ways to go about it. It's not a LOT harder than brewing wine or mead, but it is a good deal more involved; there are more ingredients, more varieties of ingredients, and you have to boil (and steep or mash, if you want to use grains). I'd recommend getting your hands on Charlie Papazian's "The Complete Joy of Homebrewing" for the basics on brewing beer; for extract-based brews, the process is identical with barley-based brewing.
Sam Adams is a lager, and brewing lagers is a bit more involved than brewing ales, because they must be fermented at controlled low temperatures, and that's difficult for most people unless they buy a fridge and a temp controller to create a fermentation chamber. However, you can get close to lager flavor with blonde or cream ales, provided you use a neutral yeast, noble hops, and do a decent job of preventing the fermentation from getting too hot. I'd bet my bottom dollar that you can brew a gluten-free beer you enjoy. Some combo of rice syrup, honey, unrefined sugars, and/or candi syrup will get you a beer that's better than any sorghum beer you can get off the shelf (provided you don't mess up the brewing process), and once you get comfortable either malting grains or using exogenous enzyme formulas, you can add much better grain flavor to your beers.