If going with new, and in the US, pretty much you're going to have to go with RX570. Going for a GTX 1650 gives you less performance, and costs more.
Checking with the US prices today (new, with warranty) from PCPartPicker:
- The cheapest RX 570 4GB is $130
- The cheapest RX 570 8GB is $145
- The cheapest GTX 1650 GDDR5 is $150
- The cheapest GTX 1650 GDDR6 is $160
- The cheapest GTX 1650 Super is $160
- The cheapest RX 580 is $170 (this one happens to be an 8GB model, though 4GB models exist, bizarrely, for more money)
Performance, from lowest to highest:
- GTX 1650 GDDR5
- GTX 1650 GDDR6
- RX 570 4GB
- RX 570 8GB
- GTX 1650 Super
- RX 580 8GB
Now, in terms of power consumption under full load: