Singles - I agree. Even doubles, there are reasonable ones.

Find a good cheap triple or higher stroller. Then you're looking at used car prices.

And I agree - a train is nice with a family, because once you're in, you're in.

But a train is more like a plane than a car; it's the subway that's closest to short commuting trips, and they rarely have bathrooms and often subway stops don't have them, either.

(Sometimes the temptation to get an RV with a toilet is high, mind you.)