No GRE offered in my country and I cannot really afford traveling elsewhere
First, not all universities require the GRE for graduate admissions, but you will need to explore that yourself. Second, under the conditions you cite, you can ask for an exception and it is possible, but not guaranteed, that it will be granted. 

The GRE is only one measure of likely success. Its only real advantage is that it is standardized. Any university wants assurance that admitted students are likely to succeed, hence they ask for such standard things. But, it is possible, in some places anyway, to provide that assurance through other means, such as an exceptional record or exceptional letters of recommendation. A prior research record can also help in some fields.