30$ a month is pretty cheap for a gym. Make a list of the exercises you can do with your free weights, and which muscle groups they target and mix and match until you have a reasonable amount per muscle group.
Arm Curls (bicepts, upper body muscles that pull up)
Overhead presses with barbells/bar (tricepts, upper body muscles that pull up)
Pull Up (upper body muscles that pull down)
Bent over single arm row (bicepts, upper back)
Pushups (tricepts, upper chest)
Crunches (upper stomach)
Diagonal Crunches (obliques)
Leg Lifts (lower stomach)
Hip Bridge (back)
Lunges (back, much lower body)
Heal lift / Toe Lift (calves, can't think of front muscle name atm)
Hammy and Quads will get plenty from just running.
I'm sorry but that's absolute bs. Apart from a 2-3 month period at a gym, I've done everything without a gym membership. Just because you can't get motivated to exercise at home, it doesn't mean that others can't. I've lost a lot of weight just by eating right + walking/running and various exercise DVDs. It's about self discipline and having the motivation to change your life for the better.
I also know a girl who's got a gym in her home and she's got absolutely incredible muscle mass after a year of lifting seriously.