Not enough info.
psu: watt and model number
mobo: model
case: what case it is
If you can find that out we could probably figure out one for you. The easiest solution though would be to go to
https://pcpartpicker.com/, find your motherboard, and your case. add them to your build and then click on the graphics card section you can sort list by price search for certain brands etc etc. After finding what one you want to go with it has links to where you can buy them and if there are promotions or mail in rebates. I would recommend adding your other parts and seeing if you need a stronger psu. in the top right it will have an estimated total for how much each part will use. and check for compatibility or other issues.
As an example I just upgraded my wife's old graphics card as it died on her She had a geforce gtx 560 and we where able to get her a Geforce GTX 950SC for at that time $139.99
Her Mobo and Case with compatible cards as an example
I hope this helps!