Agreed the $580 is high for that with 64GB
I purchased used a year ago at a much lower cost
Not knowing your location also does not help as prices can vary greatly around the globe
Here is one locally that has not been sold after weeks and it is still under the first year of apple care.
As you can see for just a few more $s IN ASKING PRICES that may or may not be firm you can be in a mid 2013 model with 2x the storage and gain USB 3 along with the benefits of the 4th gen icore
http://minneapolis.craigslist.org/hnp/sys/4527700744.html
I am not suggesting that link as a good buy, nor is it mine, just using it as an example.
I suppose if you purchased a 64gb model, you could sell that ssd for around $75 USD and purchase the 128GB for around $120
What-ever you do if purchased used, be sure to have the seller do a complete restore/reset of the OS OR make sure it is removed from his account so that it does not some how get efi locked later.
btw:
my error, the mid 2012 model do have usb 3, sorry for the error