For DIY purposes I’ll say a “precision” scale is one that can weigh down to 0.01g (0.00035 ounces). Scales this precise usually have a fairly low maximum weight (100–200g) so they are best suited for smaller batches of products, or for weighing out potent ingredients like preservatives before incorporating them into larger batches of products. Remember that the maximum weight of a scale includes the weight of your container!
To learn more about what to consider when purchasing a scale, please read this FAQ.
I highly recommend picking up some sort of precision scale if you enjoy this hobby. I started with an inexpensive one (often sold as jewellery scales) from Amazon: Smart Weigh SWS100 Elite Pocket Sized Digital Scale, Black. After breaking a few of these I upgraded to the Jennings JSR-200 (USA / Canada), and I’ve been very impressed with it—it’s lasted a lot longer than the Smart Weigh one!
As of summer 2020, I also have a Jennings TB 500—this lovely scale weighs up to 500g at 0.01g increments, and it also plugs into the wall so auto shut-off isn’t an issue! You can find it here in Canada (that’s where I purchased mine), and here in the USA. It is quite a lot cheaper in the USA ($70USD vs. $140CAD [~$105USD]), which is a bummer… but if you’re Canadian you’re probably familiar with that trend. Sigh.