This Apple MacBook Air sells for about $245.00. It’s a D grade model so it will have dings and marks but it will work if you can get past the issues that are purely cosmetic this is a pretty good deal on a MacBook Air and with a few upgrades could be even better.
You are stuck with 2GB of RAM on this model which is fine for writing and browsing but you might want to check for a macbook air with 4GB at least if you do anything with images or videos instead of this model.
You can add more storage space to this MacBook Air as you can replace the 64GB drive with a bigger module. If you’re going to bother to replace the SSD on the 2011 MacBook Air I would suggest the 256GB size. This should only cost you $100.00 or so
Because this is a 2011 model you might also want to buy a new battery for the MacBook Air which will set you back about $50.00. If you can live with the 64GB drive size I would be inclined to replace the battery first and then do the hard drive upgrade second.
Lastly, many of these older MacBook Air models don’t ship with a charger. It’s only about $20.00 for a new charger so that should not really be much of an issue.