Anyway to repair windows that won’t stay up?

By staying up I assume you mean they won't stay open. I would use something like wooden dowels to prop the windows up till you can afford to get new energy efficient windows. It's cost effective, the inconvenience is minor and in my thinking, any investment should go toward new windows that will save money in the long run. Especially if they sweat in the winter and cause mold problems.

I have seen this repair done on TOH - does it help?

How to Replace Window Sash Cords

In this how-to video, This Old House general contractor Tom Silva repairs an old double-hung window

https://www.thisoldhouse.com/how-to/how-to-replace-window-sash-cords

these sound like what we in Australia call sash windows those metal spiral things you talk about are supposed to have rope attached to them that run through a pully and the weights hold the window up when it is opened. You can replace the rope yourself if you or your partner are handymen/women

Don't be had... you can replace the mecanism to fix the problem. Even paying someone to do it will be less expensive than replacing a good window. Miss Australia is correct

They sell little spring that you tack to the inside of the Window track with a bow when the window goes down it flattens out when the window goes up and expands back up and holds the window in place

Thank you

Sorry I did not see this till now, you can buy them at any ace hardware, just tell them it’s like a spring that goes in between the window and the track they will have them hope that works for you