I am heartened to see so many here share my view, which BReece put so well: "If you don't have the money NOW, don't fool your self and think you can save FOR IT." Apparently model railroaders are, whatever else they may be, prudent and wise people.
I am not against pushing your finances for a good and necessary cause. We've all done it, I'm sure. But model railroading is supposed to be fun and relaxing, and I would think worrying about paying for something would take the edge off that.
I've always figured you don't even push the envelope on finances when buying toys. A number of years ago I bought an exotic Italian sports car - red, mid-engine, 200 mph - the whole nine yards. An acquaintance looked at it and asked, "If you don't mind, what are the payments on something like this?" I told him I didn't mind, but I had no idea: it had never even occurred to me to ask - or to finance so utterly foolish a toy purchase. The guy is in bankruptcy again, at age 66, for the second time in his life now (that, I understand, is rather hard to do because it takes so long to get out the first time and then get that far in problems again). He is not a model railroader..
Remember what Dickens said. Best to be the guy who only spends nineteen pounds six, not twenty pounds six.