Just my two cents:
Collections take years....if not decades....to acquire. I wouldn't rush it....and the long searches are part of the fun.
Once people have a modest size "collection" and they see a new locomotive or what not, they often pay for part of the new loco by selling an old one to help offset the cost. The collections that you see in magazines and on line often took decades to put together. Unless you're made of money, it's hard to put together a large collection quickly. (I opine that it's not as much fun that way....but opinions vary.)
You don't HAVE to build a DREAM layout right off the bat. My 20x7 layout was NOT very expensive to build. Granted, Baltic Birch and #2 1x4 pine were a lot cheaper in 2004....but I digress.
It's not that expensive or time consuming to get two mainlines up and running in a small to medium sized space. It's also fine to only have 2-5 locos at one time.....and some modest rolling stock and passenger cars.
If money is a concern (as it should be) I'd go for QUALITY over QUANTITY. I'd also build the best small to medium sized layout that you can afford that isn't over the top. Personally, I'd rather have a paid for, cr*ppy layout....than a big, dream layout this saddled with debt. Admittedly, us CPAs are cheap.
What I'm describing is NOBODY'S dream layout. But it's easy to do and can be done quickly...and won't break the bank.
A half baked, half done layout that lets you run trains is fine. Start small and then work your way up.
