You need scales which won't lose their tare when the battery saving auto-shutoff cuts in. That means AC power. I suggest this one
, which has a 2kg capacity and 0.1g resolution. It's the one I use for brewing and espresso.
It's not the prettiest thing but it's a lot less expensive than the Hario or Acaia, and you can't call it on your phone. On the other hand, it's not in trouble for cyber bullying and does the three things you want a scale to do: tare, hold the tare (which the Hario won't do), and weigh accurately. In addition, the plastic covers work as trays which are handy for weighing things which may leak a little -- like portafilters.
Unfortunately, the plate is too small for the bean scoops and colanders I use for roasting. For that matter, all the dedicated "coffee" scales are. I use a commercial size, "trade rated" scale which is quite a bit bigger and more expensive.
On the other hand, the little AWS may be big enough for you. If it isn't, you only need 1g resolution for roasting. You can find all sorts of scales with enough capacity to weigh your bags of greens as they come in fairly cheaply. Look here
, for instance. A little more expensive, this My Weigh KD 7000
(along with the AC adapter) is perfect for the home roaster who has room for a permanent setup, buys 10lb bags and charges at around 500g. As a matter of fact, it probably would have served me as well as my considerably more expensive My Weigh iBalance 5500.
Drop a nickel in the pot Joe. Takin' it slow. Waiter, waiter, percolator