+1
If money is a concern go the Apple Refurb route.
MacBook Air. Definitely go 8GB RAM, future proofing. Hard drive size is a personal question; 128 or 256, everybodys needs are different. Media hogs will need the extra space. You can always add an external HD, but you can't upgrade or add external RAM
As far as the original MacBook Pro, I wouldn't ever think about getting it. Yes, you can upgrade the RAM and HD later, but thats more money to think about spending. It's been almost 3 years since they've been updated, so you're buying a 3 year old machine already. According to the
MacRumors Buyers Guide:
"MacBook Pro
MacBook Pro
Don't Buy Old, But Updates Unlikely
Apple's non-Retina MacBook Pro line has been whittled down to a single 13-inch model that has not been updated since June 2012. Further updates are unlikely, as the company will likely simply discontinue the model as Retina MacBook Pro models have become more affordable and popular. The model received a $100 price cut in July 2014."