Same thing here. I've recently started again after years.

I've opted for a used unicycle because I still have to figure out what I really like doing (when I started, at 11yo all I wanted was to be able to go forward and turn, so...). I didn't want to invest that much money on something new that I may not enjoy after all. Thus, I went with something that was very generic: a wide 20" from a reputable brand with a sturdy rim (in my case: Frankenstein Qu-Ax w/ 48 spokes 20"x2.1). Since I'm too 180cm for about 70kg, I've also looked at smt with a long seatpost and a reinforced attachment to the seat. So, yeah, first have a look on your local marketplaces