Buying trains used will save you are great deal of money. There is an awful lot of second-hand HO stuff out there and much of it can be had very cheaply, if you know where to look. Check any place that deals in used goods: thrift stores, pawn shops, junk stores, antique shops, flea markets, garage sales, etc. The key is to be diligent in your search. Never pass up an oportunity to go to these places. Find out where there are such places in your area and, if you ever travel, always search for them at any town you visit. Granted, many times there will be no trains, but, if you are diligent in your search, you eventually find some. Many times you can find trains, especially HO ones, at quite low prices, but not always. There are some who want far to much money for what they have. However, the trains you do find will certainly make up for the disappointments. I've always done this and the result have accumulated a large collection.
Also, Go to model train shows if there are any in your area. There are often sellers with bargain bin HO stuff they sell at low prices.
However, having said that, $15 isn't very much money. Even if you find some great deals, that won't go far. I would highly recommend finding a way to earn some more, whther it be through an allowance, mowing lawns, etc.
Anyway, the best of luck to you in you model railroading endeavours!
