On30 will draw you down the "financial" rabbit hole real quick.
Yes, it's fun to play with the "cute stuff", but it does require more ingenuity,
space, and CASH. O scale structures, track, switches, etc are expensive.... almost prohibitively compared to HO. Sure, you can use HO track and switches, but it won't look like O scale narrow gauge track.
On30 is pretty much dead. Bachmann was the major suppler for RTR On30 motive power & cars and they haven't produced anything in years. Yes, you can buy 3D printed cabs or scratchbuild motive power like I have using HO donor engines, but it's an expensive search and rescue mission to find O scale Cal-Scale and Kemtron detail parts.
Ebay is loaded with people trying to get rid of their On30 stuff. Kitbashing and scratch building has become a necessity due to cost and availability.