So you say a computer but what do you mean?

Do you mean a laptop? If so, I'd go on ebay a second hand laptop; the more powerful the better but be aware you won't get much power for $150.

Do you mean a PC? As in you have a display (including a TV), and a keyboard and mouse? If so get a 2nd hand mini PC. There seem to be a lot available on Ebay that are within $150 and decent enough spec (8gb Ram, multicore processor albeit older ones); you will in theory get more bang for your buck for power as you're not paying for a screen and peripherals. Reality can be a bit more random between PCs and laptops.

Or you could get a SBC (Single Board Computer) like a raspberry pi 5 and case, or Orange Pi 4 and case. Storage would be an issue so you'd have to also get an SD card or budget for an external drive if you want better performance. This may be a decent route to go, as it's a fun project and can be reused for something else (like a home lab/server set up) if you decide you want to buy a more expensive laptop once you've tried Linux.

Any of these option, you will be able to run Linux including Fedora. But bare in mind that if you get a lower spec device like an SBC you may need to use a low powered desktop environment like XFCE or LXQT - this will run fine but won't be as slick as MacOS seems. That said, I had KDE Plasma running fine on my Raspberry Pi 5. While a second hand laptop or mini PC with enough RAM and a decent enough CPU should be fine with KDE or Gnome.

Whatever happens, don't expect as slick an experience as a Mac book when only spending $150 on hardware. That said, it should be decent enough to get a feel for linux.