These projectors are called simplified micro projectors (SMP). It is one kind of projector which has simplified system structure design, but with multi-function. These projectors usually uses LCD as the image system and LED as light source.
The most important thing I have to tell you is that do not keep high expectation if you decide to buy a cheap projector. It comes with less/basic features for the less price you pay.
Usually these projectors can not be used in environments with bright light. Cheap SMPs can not produce a larger picture, but you can get a decent 34 to 130 inches image in a fairly dark environment. The picture isn't too bright, so you can get the best output in a dark room. Hence think of your requirement before buying one. It would suit well for home cinema. For doing a presentation in a fairly dark room, well it will yet do a reasonable job. But beyond that, you will have to go for an expensive projector.
|UC40 and RD805 projectors|
After doing few weeks of reading on internet, I finally ordered Unic UC40 model. My budget was around 80 USD, and UC40 was the best option to go as per some reviews. Alternatively GM 60 (another reference) and RD 805 seemed to be a good option too. Later I ordered RD805 for one of my friends. It was bit hard task to compare between models as there were not much reviews on internet on these projectors.
Most of SMPs produce 1000 lumens brightness and 1:1000 contrast ratio. They have 800x450 pixel resolution, well those specs are adequate for the price you paying.
I will bring a comparative review of UC40 and RD805 in my next post.