The workforce is currently cheap compared to western countries because of the local currency's low value, and IT being one of the very few fields where people get paid in dollars.
So as a result, what would be a low wage in the west is an extremely high wage in Ukraine (e.g. $1k a month = 25k hryvnias, which is 8 times more than country's minimum wage).
It's not true that it is cheap because of the local currency low value: the IT wages were approximately the same when $1k was 8k hrn.
Ukrainian IT market is mostly outsourcing and does not depend much on the internal market and local currency, outsourcing developers usually get paid in USD (or equivalent) regardless of the hryvnia value.