Ther are two staunch camps: the DC camp, and the DCC camp, and never the twain shall mix! Those who have DC will tell you DC is the way to go, those who have DCC will tell you DCC is the way to go.
I am one of the rare ones…a CONVERT from DC to DCC!!! Here is why:
When I got back intothe hobby 6 years ago, I had some old 0/027 and some DC N scale form teen years. BUT I wanted HO always so I started buying DC HO… Then I found out about DCC and decided for easier wiring I wanted THAT feature, so quickly halted all DC purchases and advanced to DCC. I LOVE it. Ilike the idea of controlling to loco ,not the track voltage!
1} On some DCC systems you can run one DC loco, so you needn’t be worried immediately there with that. {mine has that}
2} As mentioned the old locos can be converted to DCC. If you can learn to do it yourself you have only some hobby time and a few bucks for the decoder to cost.
3} there are some nice DCC OnBoard locos for around $50-$100. I am on a very tight budger and have managed to aquire quite a roster.
4} There is also this new-fangled thing called Ebay auction site. There you can find locos of DCC nature that have been converted or came DCC equiped. They can also be relatively cheaper.
5} you can aquire a replacement loc say, once a year at Christmas to spread out the costs.
6} MAybe your brands of older locos are cheap locos that may have sentimental value but not good pullers? so maybe you want a “better” loco?
7}Some DCc systems {Bachmann’s EZ COmmand, and DIgitrax Zephyr Xtra} are relatively inexpensive and can be added on to get more amps to run more locos as you progress along.
8} SOmetiems our eyes are bigger than our stomachs…meaning we want MORE than we can actually handle… many on here will say that by themselves they really can only control 2 or 3 trains at once, so the need to have 15 trains is a moot point. You can, with your DCC system’s amps allowable-or with extra amps, run a con