Fingerboard is great training tool for your finger strength. It's quite cheap, you can place fingerboard in your house (or apartment). Idea is easy: You can pull-up or hang on fingerboard, where you have lot of holds (small, big, mediu. Crimps, pockets, etc.). See below some nie movies about training.

http://www.metoliusclimbing.com/pdf/Training_Board_Brochure.pdf