SCI/other credible journals for low budget authors I have done some work and I thought of publishing it. This is my first attempt to publish. After searching a lot, I found out that SCI indexed journals are good. But I am seeing publishing price at about $1500-$3100 which is absolutely impossible for me. (Just out of question). My work is on improvement in image processing, being specific, matrix encoding algorithms.

I am putting my question here after searching too much, so any hint would help. I am almost about $100-$150 budget. I don't understand how sharing info could be so costly. Is it not done as a service by scientists/Phd students collectively at some reasonable price ? 

Its a baffling experience to me, specially this listed price on journal websites. In my country this amount means fortune.
Many journals do not charge any publication fees at all.  For example, subscription journals often fall into this category, and in most fields there are plenty of subscription journals.  If all the journals you are finding charge fees, then I'd imagine you aren't searching broadly enough (although maybe publication fees are particularly common in your field).

Furthermore, journals that charge publication fees ought to give fee waivers to authors from developing countries.  Their web sites often explain the details, and if they don't you can write to them to ask before submission.  They might in principle say no, but it can't hurt to ask.