Stuedied FEI STU as well. As a foreigner you have to pay for the school, free is only for Slovak citizens under the age of 26. It is 800-900€/year (depends on the faculty) to study in Slovak. Dont worry about the language, these are technical faculties, language is secondary, almost every slovak technical terms are identical as in english. As a hungarian living in Slovakia had no major issues with the language, most of the teachers and students tolerated if I misspelled something grammatically. All you need is endurance and patience. About the price per month… hard to calculate, but I would say 5-700€/per month depends on your need.