For the longest time, On30 was known as the 'whimsy scale', the red-headed stepchild of the hobby from which nobody wanted to be openly associated. Times have changed and now there are folks doing decent stuff in that gauge which are devoid of the whimsy that was a staple for On30.
i had several visitors to my layout for NG convention in September who said that they now had a healthier respect for On30 after seeing some of the local layouts that don't look like a Disney version of Malcom Furlow's worst dream...
On30 is very tempting, the locos [especially steam critters] are fairly cheap, but other rolling stock is not ..
It used to be inexpensive for most of it-
-Then one day, it just stopped being so.You used to get Bachmann On30 cars all day long for $20 or less. Good luck with that now. I really believe they flooded the market, drive down the price by doing so, and now it's tough to get Bachmann to realize they can sell cars again at a moderate price because all that original On30 stuff is in people's hands, and it now trades for premium prices.
I'm just so glad I got into on30 when it was very affordable.