On: Amazon ElastiCache Details - Managed Memcache

[philwise]

That is pretty pricey. 1GB of RAM from crucial is $10. 1 GB of Memcache from AWS, (assuming 3 year amortization) $1900.

Obviously there is overhead, but if you have machines already and they are not maxed out on RAM then the $10/GB price is not far of the real cost.