docs: ongoing cost details (#152)

* added ongoing costs section to contexts.md
* added cost estimate links

site/content/en/docs/Concepts/contexts.md

@@ -178,6 +178,27 @@ can still be interrupted if total demand for on demand instances in an availabil
 full details see [Spot Instance Interruptions](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-interruptions.html) 
 and [EC2 Spot Pricing](https://aws.amazon.com/ec2/spot/pricing/).
 
+### Ongoing Costs
+
+Until a context is destroyed resources that are deployed can incur ongoing costs even if a workflow is not running. The
+exact costs depend on the configuration of the context.
+
+Amazon Genomics CLI version 1.0.1 and earlier used an AWS Fargate based WES service for each deployed context. The service
+uses 0.5 vCPU, 4 GB memory and 20 GB base instance storage. Fargate pricing varies by region and is detailed [here](https://aws.amazon.com/fargate/pricing/).
+The estimated cost is available via [this link](https://calculator.aws/#/estimate?id=9a67ba7845199cf108d85ae0f9b8176253266005)
+
+After version 1.0.1, the WES endpoints deployed by Amazon Genomics CLI are implemented with AWS Lambda and therefore use
+a [pricing model](https://aws.amazon.com/lambda/pricing/) based on invocations.
+
+Contexts using a Cromwell engine run an additional AWS Fargate service for the engine with 2 vCPU, 16 GB RAM and 20 GB of
+base storage. Additionally, Cromwell is deployed with a standard EFS volume for storage of metadata. EFS [costs](https://aws.amazon.com/efs/pricing/) are volume based. While
+relatively small the amount of metadata will expand as more workflows are run. The volume is destroyed when the context is destroyed. An estimated
+cost for both components is available via [this link](https://calculator.aws/#/estimate?id=8ccc606c1b267e2933a6d683c0b98fcf11e4cbab)
+
+Contexts using the "miniwdl" engine use EFS volumes as scratch space for workflow intermediates, caches and temporary files. Because many genomics
+workflows can accumulate several GB of intermediates per run we recommend destroying these contexts when not in use. An estimated cost assuming a
+total of 500 GB of workflow artifacts is available via [this link](https://calculator.aws/#/estimate?id=4d19b43aa86fcc3af199c425bfcc55193592cbb4)
+
 ### Tags
 
 All context infrastructure is [tagged]( {{< relref "namespaces#tags" >}} ) with the context name, username and project name. These tags may be used to help