My general thought on almost everything "collectible" (including for example- Lionel trains, Corvettes and antiques) is that values would drop rather then grow in the next few years. I just bought a very good condition # 6560-25 (red body)- built in 1956- for just over the bottom price listed in Greenbergs. I didn't "steal it", but paid a fair price IMO.
In general, what do OGR Forum people is the future in terms of value for Lionel products of the postwar, and MPC eras? It would seem that many would prefer the newer trains with more features, at least for running. There are some real bargains out there right now, it seems to me.
Operating Work Crane