Your observations are correct. Aluminum rails are relatively expensive. Wood rails present problems if you want to remove or rearrange modules much.
I think most people in this community (versus almost none in Eurorack, even Eurorack DIY) opt for wooden rails and wood screws. I use aluminum rails, and would not want to put up with wood, but they’re not cheap. (On a per inch basis the cheapest are Vector rails bought in a package of four 60" pieces and cut to length, but that’s a lot of modules’ worth and is a large upfront investment.)
Here is a third option, if you have access to the equipment for it: