Divx readers

What they do
They allow you to watch a divx on a television, just like ordinary DVD readers.
 
Quality to consider before purchasing one

1) Compatibility and possibility to update it regularly. A good Divx reader can read videos both in a Divx format and Xvid format. In addition, as these codec (especially Xvid) are updated quite frequently, the producers must have a website from where you can download updated firmware, otherwise you won't be able to see a lot!

2) Chip. The quality of the chip that is integrated in the reader is very important. If you can, pick a reader with a last generation Mediatek chip. With less recent chips, you will have problems at seeing divx with a high bitrate (such as 1000/1100 or more kbps). You will also have problems with the sound (especially if AC3; and if you have unusual audio formats such as ogg vorbis, you won't have a chance); there are no problems with an mp3 audio with constant bitrate; however, do keep in mind that poor quality divx readers will have problems with mp3 variable bitrate (VBR).

The first generation chips are the Sigma 8500; the second generation ones are the ESS and the third generation ones are the Mediatek.

Having said all this, do remember that if you have bought a poor quality divx reader you can always re-do the encoding of your divx (that is converting it using parameters that are accepted by your reader). However, this procedure can be rather time consuming...
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The cost of a divx reader can vary between 70 and 200 USD, depending on where you buy it from, its quality, its characteristics and so forth...
Brands to keep in mind (Divx readers sale)
The main brands are slowly entering in the arena. However, brands such as Philips, JVC, Yamaha are refining their products and increasing their divx standards.

Between the available divx readers, you should prefer the ones with Mediatek chip. One of the best divx readers (in this moment) is Pioneer 575.