If you'd like your child to learn the Spanish language, you may want to consider using Spanish VHS tapes. The advantage to learning by video opposed to books is that children have more fun listening to songs and watching the cartoons that many of these videos feature. They will also be more likely to stick with studying if what they're doing doesn't feel like work.
Another option to think about aside from educational videos are VHS movies in Spanish. A large number of popular films have been released on VHS and feature Spanish language audio tracks. A child following along with a movie that he's familiar with could help him absorb the language easier and have fun at the same time.
Both Spanish language movies and educational learn Spanish VHS tapes can be purchased online, either used or brand new. To save a bit of money, you may want to look into purchasing used VHS tapes from online auction websites. Afterwards, once your child has learned the language and the tapes are no longer needed, you could resell the movies from the same auction site. This will allow you to recoup most of your initial investment, and you'll be passing the VHS tapes onto another family that could benefit from them.