Especially for those living in the city, space is a premium. And not only do exercise equipment cost money, they cost space too. Take for example a treadmill, possibly the best exercise machine there is, and consider the amount of space it uses up. Same space can easily accommodate a bureau instead. Or a desk.
Sure, some equipment are foldable and can be hidden. But the exerciser might also get too lazy setting it up again and again. So what can be a great solution when space is a resource you don't have?
Go for other exercise accessories instead!
Think of dumbbells, leg weights and jumping rope. Skipping rope is a great cardio activity, leg weights will provide the resistnce you need as you go up and down your stairs (or a step stool) and dumbbells will help in toning those flabby arms.
You can also get an exercise video instead (or a bellydancing video for that matter) and use your living room, however small it is, for some taebo and yoga. The thing is to just find alternatives and work around your limitations. DO NOT GIVE YOURSELF AN EXCUSE NOT TO EXERCISE. You owe yourself a healthy body to enjoy the life you have!