I wanted to buy myself such a toy. Yet, the ideal — LEGO Mindstorms, but one drawback — the price. Quite expensive for a poor student.
There is still Aurdino, prices are excellent, great choice of parts, opencor... but there are 2 disadvantages:
1) Need to buy many parts to make at least a machine
2) the Language in there, if I'm not mistaken c++, which though powerful, but to write something serious on it, I'll be a long time, too much they need to think about language.
Actually the question: are there any other options like toys and what you can advise?