I recently did a 3×9 to a 1×10 conversion on my hardtail.
I bought a 32T raceface chainring on amazon for 25$ and bought a sun race 11-42 cassette also on amazon for 40$. I then bought a rear deraileur and shifter on jenson for around 60$ combined(Sram GX DR and X9 shifter). Swap was super easy and for the price I felt like I got a pretty good deal, especially because I did the work myself.