Overweight people tend to be targets, because most want a "quick fix", so companies promise that to get them "hooked"........ you are right to be leery of most of them. Anything that sounds too good to be true, promises to be a waste of money.
There is a lot of free information regarding weight loss. Take a look at some of the National Institute of Health or FDA websites; you will find information regarding diets, food pyramids, ideal weights, etc. Mayo Clinic website has good information, also; I often use it as a reference. Check out Dr James Beckerman, here on MedHelp; he's got some really good journals that you can read.
There are also free videos that you can watch online for various exercises. Try yoga; there are a ton of videos that you don't have to pay for. Not sure if you can download them, but you can certainly watch/do them online. You might also find online videos of Pilates or other forms of exercise.
Walking is always an excellent form of exercise.
I agree that gym and food club memberships can get expensive and they usually aren't real long term anyway, so best to learn all you can about nutrition and exercise and formulate your own plan that you can stick with.
You might try watching yard sales/thrift stores, etc for used dvd's and/or books, which can be purchased much less expensively than buying new. You only need to find one or 2 dvd's that you like, to have what you need.