Solid core power cords under 300$ - List of manufacturers ?

You need to be careful with solid core PC's. Too much bending can lead to wire fracture.

Most aftermarket power cords we talk about in these forums are not UL listed. Years ago there where a few makers of solid core, however only one comes to mind now, Tara Labs RSC (rectangular solid core) I think they made 2 versions. There are products in the DIY market that allow one to construct ones own SC power cord.

" Romex will outperform any manufactured PC"
Not true, Romex uses low grade copper, has no shield and in some system configurations, would introduce noise. I have had that experience.