Targus mouse
Hi, I'm in the same situation as you, I think the Magic Mouse is a bit expensive and I don't think I need al the multi-touch features that I have on the trackpad. And getting an USED Mighty Mouse doesn't seem like a good idea...
I searched a lot and the best I could find is the Targus Bluetooth(R) Laser Mouse for Mac(R) AMB08. I think it looks great, it's more precise, it has a 4-way scroll as well, customizable buttons and it's built for Mac! It goes for $35,99 (
http://www.targus.com/us/productdetail.aspx?sku=AMB08US), which is cheaper that the MM and it's brand new. I think I'm gonna get one this weekend, so if I do I'll let you know how good is it.
I hope this helps and you can check out my post, there are some pretty good replies there (
https://forums.macrumors.com/threads/1231825/).
Cheers.