Personally, I would go for an older MacBook with 4gb of memory.

One of the options I was looking at was this It is an older Macbook with 2GB of ram and running OSX 10.6. Would this work? or no?

You will also need $99 for a developer account.

It is my understanding to download the software and begin it is free and you only need to pay the $99 to release it into the store? I could just get the software and only when I felt like publishing an app would I pay the $99.