$25 a month sounds really cheap for a gym actually. My 'gym' costs much more than that. But I justify the expenditure to myself because I think my health is worth something.
But I realize not everyone can afford it. And if you can't, I do think body weight exercises can be effective - but you need to be self motivated and know what you are doing.
Not sure what you were doing as far as body weight exercises but Zuzana Light or Bodyrock.tv, have some good workouts you can follow online. Calisthenics, parkour or street running might be fun to add to the mix. Try a few handstand pushups... you will be lifting some serious weight.
If you want to invest in a minimal amount of weights you could try p90x. Some have had success with it. Speaking for myself only, I would not be motivated to work out at home by myself so any investment in that regard would be a waste for me. But you have to know yourself to know whether it is worthwhile.
Then again, you can always fork out the money just for a 'trial' month and see if the gym works for you. You might actually love it there and if so you will reprioritize what it's worth.
Anyway, good luck.