no offense...but it really depends on you're reaction time before buying a high response time monitor like 144hz or 240hz.
i honestly seen some dog shit players either playing too high or not quick enough to really benefit from one,ton of other factors too if you're skill level isnt up to par.
also met a ton of god players using 60hz cause their budget wasn't enough...its an insane skill to predict player moves before they happen,but pros do it cause they know the timing 100% in games for movements...really blown away hearing top fraggers still using 60hz and just fucking slapping people.
Power supply on the other hand,Huge NO on trying to find a "Budget" friendly PSU....i almost made that mistake
its something you're gonna be using long term so get at least a gold+ rated,dont give your computer build any chance to fuck you over on cheap low rated parts...you get what you pay for....could easily roast you're gpu,motherboard and ram with crap power supply.