The primary benefit of a scale is fairly obvious, precision in measurement. If a recipe says two medium tomatoes, there's some ambiguity there, but there's none in 5oz. Using a scale allows you to get exactly at the intent of a recipe. Of course, that's assuming the the recipe uses weights as a unit of measurement (a lot of internet ones don't, for instance).
If you find yourself regular seeing recipes that use weight and think to yourself, "I wish I knew how much 10oz of Okra was" then you should get one. If you find you're never really bothered, then you don't need one. I think it largely depends on the type of cook you are. That being said, there are some uses (i.e. molecular gastronomy or following a Thomas Keller recipe) that require the scale, but at that point you'll quite obviously be bothered by not knowing.
Close to the bottom of the line will work fine. I use a scale pretty regularly in the kitchen. We spent about $40. I don't think there's any need to pay through the nose for one. My experience was that the cheapest ones felt shoddy, like they'd fall apart quickly. They were also ugly. We got the cheapest one that looked nice (it's always out) and felt decently constructed.
Two paragraphs of personal experience, skip if you want:
I'm a bit mixed on the need for one. We got a scale for our wedding and didn't use it for a long time. As a fairly experienced cook, I've always enjoyed tinkering with recipes and the scale implies an amount of precision that I didn't feel necessary, especially when making a dish from a recipe source that I don't consider to be a "bible".
However, about 2 years ago, my wife and I got much more serious about cooking, getting in to molecular gastronomy, sous vide, and following some of the worlds best chefs with a bit more interest. With molecular gastronomy, the weights need to be quite precise so a scale is a must. We also started cooking Thomas Keller and Grant Achatz recipes and I was suddenly faced with books that measured everything in grams with no tsp, tbsp, or cups. So not only did I have to use the scale, but I also trusted the chef enough to want to get as close to the original recipe as possible. Since then I've used the scale more in regular cooking to get a base line when a weight is used, and adapt from there, but I think that's more a convenience than a need.