If your just playing around Logic Studio would be way too much for you. Pricing is not bad anymore for Studio. Watch those educational prices though. There is no upgrade path to them. Meaning the next major release would require you to purchase the full program again, there is no upgrade option on educational software.
That said I really am a huge fan of Logic (90% of the reason I stay will Apple), but I am doing a lot with it. For just messing around with something a little more then garage band I would say Logic Express will suit you just fine. Back with Logic 7 I could not justify the $999 price point of Pro and when with express. It works well for more then just messing around. So I think express will be a good fit for you.
Take your time with it too. Although Apple has done a lot of work at streamlining Logic, some parts can be somewhat harder to learn. Logic was always the beast with the highest learning curve. Apple made it better, but still do not expect it to be garage band with more power.
Oh, also with Logic express you still get all the software synths and FXs and all that, mainly with express you will be limited to something like 48 audio tracks or something like that.