You will get fair value in graphics cards at every price point.
If you play fast action games, budget more for your graphics card.
I might guess that a GTX1050ti would be appropriate.
The graphics card is what determines the wattage you need for a psu.
Here is a handy chart:
http://www.realhardtechx.com/index_archivos/Page362.htm
A GTX1050ti needs only minimal power, but you will find that a 450-550w psu will not cost any more and will run a GTX1060 or GTX1080 in the future.
More important than wattage is the quality of the unit.
I know you have a limited budget, but the last place to go cheap is the psu.
Buy a tier 1/2 unit from a quality list such as this:
https://linustechtips.com/main/topic/631048-psu-tier-list-updated/
I particularly like the Seasonic focus gold units.
They are often on sale this time of the year.