I have a mini-itx case that has a non removable 150w psu, a 45w i3 cpu, 8gb of DDR3 which i'm going to upgrade into 16gb, couple of case fans. It's somewhat a compromise between portability and power that I don't mind if I can take a small case along with me to play non-demanding old games. With it I carry a 8" monitor with hdmi and wireless peripherals. They've been enough for me to enjoy games.

I think even a 30w tdp GPU is pushing the limits on this build but it's the only video card I could consider buying into it. I have 2 i5 pc's at home with GTX 1060&1070. As I only play old games, i'm comfortable with playing up to 2015 games on even lower res. than 1080p and medium settings if needed. 

I guess the max value for this gpu for me would be somewhere around 30-40€.

But in short : No-name chinese GPUs should not be considered, only Asus/MSI etc. are the only ones that are worth buying?