You know the old saying: If something seems too good to be true it probably is. That\u2019s the case with the data plan for Amazon\u2019s hot new Kindle Fire HD. Amazon didn't lie when it said the Fire HD comes with a data plan that will cost you $49.99 a year for 250 MB of data.\n\tBut what the giant e-tailer didn't say very clearly (and what few, if any, tech writers seemed to notice) was that when you use up those 250 MB \u2013 which will happen very quickly, especially on 4G LTE -- you\u2019ll have to pay $30 to AT&T for the next 3GB of data. (Or you could buy 5GB for $50.)\n\tThat's a huge gotcha for most people who will use the Fire HD and it calls into question claims that the new tablet will be much cheaper to use (purchase price is another issue) than Apple\u2019s iPad. You'll also notice that Amazon was very quiet about who was going to be the carrier for that wireless data. It\u2019s AT&T, a carrier with a reputation for spotty wireless network performance.\n\tA spokesman for AT&T told me that Ma Bell has an exclusive arrangement with Amazon for the Fire HD, and that people who hit the 250 MB limit will have to go the next tier \u2013 for more money.\n\tI don\u2019t think that paying $30 a month for 3GB of data is outrageous. It's the going rate. But what steams me is that Amazon made the claim that its "revolutionary" yearly plan means that your data bills will be trivial. They won\u2019t be, unless you do nearly all of your Web surfing, video watching and so on via Wi-Fi.\n\tTo see just how meager 250 MB really is, take a look at AT&T's own online data calculator. Let\u2019s say you like to listen to Pandora or another streaming music site on your way to work. Just 30 minutes of music a day will run you just over 1 GB, which is four times that monthly allotment. Eighty minutes of high-definition video, less than the length of a movie, tips the meter at 400MB, while viewing 50 Web pages a day sucks up 260MB in a month, according to the calculator.\n\tFirst Look: Amazon's New Tablet Lineup\n\tMaking those limitations all the more galling is one of the tablet's big selling points: it is designed to run on a very fast 4G LTE network. There's no point in having that much speed if you've used up your data allotment in just a day or so.\n\tYou can always use the tablet's built-in Wi-Fi connection to download and surf for free. There\u2019s nothing wrong with that, and Amazon claims that its implementation of a Wi-Fi technology called MIMO makes the Fire HD much faster than the iPad when both are connected to Wi-Fi. I have no idea if that\u2019s true, but I do know that Amazon makes the boast: "No hunting for Wi-Fi hotspots."\n\tBut you'll be hunting. Unless you want to pony up another $30 a month, and if you do that for a year, as I expect that many people will, you'll pay $410 a year ($30 a month for $12 months, plus the annual $50 data fee.)\n\tI'm not saying the Kindle Fire HD isn't a good buy. I have yet to use one or read a thorough hands-on review, so I simply don't know.\n\tBut I am saying that Amazon's highly touted data deal is far from adequate, and the company should do a better job informing consumers of its limitations. If you buy a Kindle Fire HD, be sure you know what you're getting in to.