chances are you would only maybe sell a couple of images for 50c each. i think to make any money you need to do work for someone with an agreed price.
Well - you are giving up your copyright for 50 cents. The purchaser can do what they like with your pictures without having to pay you anymore money. I don't think it is that great a deal for the photographer.
I used to have a couple of hundred images on a similar site. I was making less than $8 a month from it... some people are making over $100 a month... but they have over 5000 images out there.
The copyright is a moot point as the images that really sell are not worth selling for any other purpose, such as people in an office environment, a stapler, a cup of coffee etc.
Landscapes and scenics really don't sell well at all.
Stock photography is a numbers game. Very few photos are likely to deliver much more than a couple of thousand $ at an average of about $175 per use. To make a living at stock, you need to have thousands of photos out there.
To be really successful at stock - you need to ask yourself - why would an advertiser or publisher need this photo? What does it say? If you can't answer what the photo is about and why an advertiser would use it in a single sentence, it probably won't do very well.
There are a lot of books on the stock business out there with invaluable insights for people who really want to get into the field. It can be quite lucrative if you have an eye for commercial photography and are prepared to work really hard at it. It will also take a few years to develop the critical mass of photos needed to pay a regular income - 2000 - 3000 absolute minimum.