What GPU and PSU should my friend get?

Solution
You can buy a GTX750ti in the low end of your gpu budget range.
It is the strongest card that a 250w psu will support..
That assumes you pick one without the need for an aux 6 pin power lead.

If you want stronger, something like a GTX960 would fit.

For that, you would want at least a 400w psu of decent quality.
DO NOT buy a cheap psu.
Look for Seasonic xfx, antec for starters.
They will be near the upper range of your psu budget.
You can buy a GTX750ti in the low end of your gpu budget range.
It is the strongest card that a 250w psu will support..
That assumes you pick one without the need for an aux 6 pin power lead.

If you want stronger, something like a GTX960 would fit.

For that, you would want at least a 400w psu of decent quality.
DO NOT buy a cheap psu.
Look for Seasonic xfx, antec for starters.
They will be near the upper range of your psu budget.
 
Solution