Texas Instruments TI-84+ Graphics Calculator

The TI-84 is a good example of where free market pricing fails. As we all know in microeconomics, the price of commodity goods and services is determined by supply and demand. This is generally a good thing as a merchant can optimally sell their wares by pricing it where the per unit revenue * purchase volume is maximized. Unfortunately, this doesn't work out very well for consumers when demand is inelastic, and especially when this is due to artificial external constraints, such as institutional policies. What do I mean by all of this? Well, the TI-84 is in itself not a bad product. It's a sufficient graphing calculator with an established reputation and well-known format. However, the actual utility of the product and its inherent value to users does not match its price, especially relative to its alternatives. After all, the TI-89 is a far superior calculator that can do everything the TI-84 can do, and do it much better (higher resolution screen, faster processor, more memory, more programmable, wider range of software, more graphing and calculator functionality, including 3D graphs, solving of differential equations, etc.), but the TI-84 costs about as much as the TI-89. In fact, you can actually get a used TI-89 for quite a bit less than the cheapest used TI-84. So what on earth is going on? What's the invisible hand of the free market doing? Well, it's exploiting the fact that many schools nowadays prohibit the use of the TI-89 because of a (mostly irrational) fear of cheating. The argument is that anything above a TI-84 is too powerful (i.e. it's _too good_ of a calculator), and students would be able to use it to solve test problems automatically. Well, while this is true to some extent, when I was in high school the TI-89 was allowed, and only the TI-92 was prohibited (due to the similarly unsound argument that having a QWERTY keyboard allows it to be used for cheating more easily--really, that's what school officials claimed), and arguably that AP Calculus program produced higher caliber students and was more academically vigorous than the same calculus courses that today ban the use of TI-89s. Additionally, you can actually add differential equation solving functionality to the TI-84 fairly easily, and it's just as easy to store/view notes on. So it's unlikely that banning TI-89s would prevent cheating to any meaningful degree. So it's really difficult to justify spending more for a used TI-84 than what the far superior TI-89 costs. The situation is even harder to accept when you consider that about 99% of the functionality most students buy their TI-84 calculator for can be duplicated on their smartphone just by pulling up Google. In fact, a smartphone with its browser opened to Google is actually a superior graphing calculator than the TI-84 in many ways. If you install an actual graphing calculator app, then the smartphone wins hands down. But, alas, many students simply don't have any choice but to purchase the TI-84. It's a wasteful situation that rips off students and inflates the price of TI-84s beyond its value as an actual graphing calculator. And if you're not a student, or you're a student in a more enlightened math department that doesn't ban cheaper and better calculators, then there's absolutely no reason to buy a TI-84 instead of the TI-89. The TI-89 has a better key layout and interface, giving you easier access to calculator features, and it's much faster and more powerful. And, especially for programmers, the TI-89 is much funner to program for and easier to program on (e.g. you can create a 3D flight simulator instead of just a 2D side-scroller). If the TI-84 were priced about 40-60% cheaper, I'd give it a 3- or maybe even a 4-star rating. But given that the TI-89 can be had for less, and the prevalence of cheap smartphones, tablets, and handheld gaming devices like the PSP/Vita/DS/Pandora/etc. that all pack so much more value and make the TI-84 look like an antique, the TI-84 is just not worth its current price (new or used).