Recently (2020 Oct 27) I have confirmed my education by the US standards: 100.50 semester hours of undergraduate credit
A typical diploma in the US is 120 semester hours. So, you're a bit short.
Be aware, however, that each school will make its own determination as to which classes can be transferred. Typically, they will look at the syllabus and determine which classes are comparable (this may be difficult in your case). So it is not at all guaranteed that a given school will count all 100 hours.
Further, virtually all schools have a "residence requirement." Even if they agree that all 100 hours are equivalent, they may not allow you to transfer more than, say, 90 hours. The thinking is that if you are going to earn a degree from University X, you should take a significant number of classes at University X. Otherwise, students could do all their coursework at school X and get the degree from school Y.
Finally, note that there are usually "distribution requirements" -- despite your plans to major in math, you will have to take classes in many subjects to earn a degree. I do not know whether this is also true in the Russian system.
How much may it cost?
Thirty credits would probably cost about $10,000. This will vary hugely depending on the school you attend and the financial aid you qualify for.
Note that despite of having no funding and no access to libraries and scientific databases I did a very advanced math research (some of which is peer reviewed and published).
Understood, but unfortunately it is difficult to convert non-University work into a degree. On the other hand, some employers might (wisely) overlook the lack of a degree.
What can I do?
If finishing the degree at the Russian institution is still possible, that would probably be fastest and cheapest. Failing that, I would look for a reputable, local university with a generous policy on transfer credits. Other answers have also suggested some accredited online schools; this may be a good option as well.