dell optiplex 7010 psu

What form factor is your 7010.. (MT, DT, SFF, USFF ) which makes a big difference in which PSU will work. In addition the recommended PSU for that GPU is 450W. I would steer clear of budget power supplies and look at a 500W 80 plus PSU. Again a lot is determined on your system's form factor.

"psu I need for under £20 or $30"

This is not a negotiation.

There are zero units for that price that wont fry and die killing everything.

there is a reason why working unts cost  £89 or more.

https://www.amazon.co.uk/EVGA-100-BR-0700-K3-Bronze-Power-Supply/dp/B07G6683R5

used Dell OEM 460w psu for MT.