I’m sitting typing on one just now – bought second hand a couple of years ago for £300 ish so its a fairly steep price for something that age now -although I’m comparing a private sale to a dealer. (EDIT – just checked back – paid £400 in 2011(!!!) and £240 for one in 2014)
They’re not making it particularly obvious its a 5 year old, second hand computer. This white UNIbody ones are little bit prone to cracking – not seriously enough to effect function but you can be pretty certain theres cracks around the screen hinges and the power socket. The rubber base is known to delaminate – with a bit of persistence apple will supply a free replacement even though strictly speaking the warrantee and recall/replacement scheme have both expired. The didn’t mind replacing mine even though I’m not the original owner. – with those things in mind I’m surprised they’re not making any statements about condition
4gb of memory is going to struggle a bit with current system software (or Yosimite), 8 would be better and you have the potential to put 16 gb in that model.
8-16gb and an SSD in ours (we’ve got two now) and they get on with everything very happily, but in the spec advertised its going to get a bit hot and bothered (with browsing as much as anything else, despite doing 3d work and video editing on mine its some of the ads on STW that cause the machine to labour)