Well i do know a thing or two.
Panel type is not important for gaming. You just need a panel with enough hz which Will most likely be a tn
MS response time does matter however most cheap monitors have 1 ms response time. (Mine does at least).
G-sync Can often be found in budget monitors. (Mine has it as Well). And the Colours are less important unless you are some sort of artist, so a budget monitor Will so just fine for playing cs