Am new to buying used trains and need help and advice on a possible purchase. ... but are there reasons or instances (i.e. roadname, type of item, etc.) when an item's fair price/value would command prices exceeding that 50% threshold?
you need to take a step backward to see the forest for you've answered your own question. put two or more people who are searching for a particular piece in the same room and you will typically only then discover the true value of an item. the 50% figure is a modal average based on the glut of products on the market today. every week i see C9-C10 MTH locomotives, likely bought by speculators, sell for a fraction of their original MSRP which is typically ~30% off to begin with. if you merely want a locomotive in a general class, you can easily find 50% off bargains daily. if you are searching for a particular piece, however, there is always the slim chance there is another modeler who's timing is fortunate enough to see the same offer. i don't look around for much modern O these days, but when i do see a piece from any era that i've been searching for, it would certainly have the tendency up my interest and probably my proposed budget.
good luck with your search...gary