Cool tech gifts under $100

This post comes from Jeffry Bartash at partner site MarketWatch.

Electronic gadgets are huge holiday sellers but it's hard to find really cool stuff for $100 or less. Most of the popular items such as iPads and laptops cost considerably more.

With a half-nod toward thriftiness in these tough economic times, here are some gifts to consider that won't cost more than a C-note.

uNu battery case for iPhones ($35 for the Power DX-1700B model ). Are you constantly running out of juice? The uNu might be the answer. It's a nifty device that protects your iPhone from damage -- and recharges a dead battery. That's because the uNu is a battery pack shaped like a cover.

Beyond Talk wireless plan ($35 a month). Want iPhone capabilities without iPhone costs? Sprint-owned Virgin Mobile has the best-value plan among the major carriers. Beyond Talk allows unlimited text and Internet. The catch: Voice minutes are limited to 300 and customers have to pay full price for a phone. Still, the plan is great for teens who love to text and for adults who use the Web much more than they talk. Android phones ($100 and up) can be used to check the weather, catch a bus, find movie times and search for nearby stores. Most also include GPS and provide maps and navigation. Also available at Best Buy.

Klipsch Image S4 headphones ($79 and up). This new classic is one of the best deals around for quality portable headphones. Looks and sounds much better than the junky earbuds that come with most players. A new version, the S4A, allows users to control their Android phones through a switch on the headphone wire. A similar version already exists for the iPhone. So leave your phone in your pocket. For boys and girls, check out the Skullcandy INK'd Earbuds. At just $14 -- no need to worry about kids losing them -- these solid-sounding earbuds come in nearly 20 colors.

The Kindle. The newest, smallest and cheapest Kindle yet is just $79, weighs less than 6 ounces and fits into a backpocket. It's a great time to get a Kindle because it now can be used to check out books from thousands of local libraries. Users do have to accept some "screensaver" ads, however. Not to be outdone is the Nook Simple Touch by Barnes & Noble. The cheapest touch-screen version costs $99 and "has no annoying ads," the company says. It is 1.5 ounces heavier than the smallest Kindle, however.

Livescribe Smartpen (starting at $100). Scribble your notes and drawings on special white paper and then upload your work to a computer with this device. The Smartpen is fatter than a typical writing instrument, but people who take lots of notes swear by Livescribe. Oh, the pen can also record a lecture while you take notes. Software to transcribe notes into editable text is sold separately. Post continues below.

Audioengine W2 ($99). Send music from an iPod, iPhone or iPad via Wi-Fi to a stereo with this small adapter. The Audioengine W2 got good reviews when it first came out, but after a price drop, the device can now be had for under $100. Audioengine calls the W2 the "dockless dock." It will work anywhere in the house.

Roku 2 wireless movie streamer ($50 and up). These fist-sized Wi-Fi devices connect easily to a TV and enable viewers to download HD-quality movies or music from popular services such as Nexflix, Hulu, HBO, Amazon and Pandora. Lots of devices these days can perform similar tasks, but Roku does it with smaller, cheaper hardware. The mid-priced Roku 2 HD player might offer the best value.

Vizio sound bar ($98). Most built-in speakers for glossy flat-screen TVs sound dull and tinny compared to true home theaters. If you don't want to shell out for pricy speakers or clutter up your room, check out the growing number of sound bars such as the Vizio VSB200. These speakers are long and narrow and sit unobtrusively in front of or below a TV. They deliver excellent sound for their size and even do a decent job mimicking surround sound.

Monoprice and Accessories4less -- These are the Radio Shacks of the Internet age. No need to spea bundle in a box store on fancy name-brand cables that cost almost as much as a Blu-ray player. These online audio-video sites sell all kinds of good stuff cheap -- HDMI cables, speaker wire, digital-audio connections, speakers and even refurbished receivers from major manufacturers such as Denon. Everything you need to set up your home theater is here. A good HDMI cable, for example, costs a few bucks. Your local retailer might charge as much as $90.

Smartphone apps. Here's a gift for yourself. Thousands of software applications are available on iPhones and now Android devices that open up a world of possibilities. Some are free, others cost a few dollars. Be imaginative when searching the Apple app store or Android Market . Apps can be used to lock doors, for instance, or change the thermostat via a wireless home network. A growing number of apps allow users to control network-connected TVs and stereos from brands such as Samsung and Pioneer. In some cases the phone apps are easier to use than the original remotes.

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