Well for babies that age, they usually will learn from their care-givers. So show them the things in the room and at home. Bring them for walks and show them colours. Sing to them and have them hear songs - you will be surprised to discover that babies as young as a few weeks like some songs and not others. The experiences that you give them will entertain them.
You could also invest in toys for slightly older kids, say 6mths to 9mths ans allow your child to play with them a little sooner. More value for $.