I am unsure on the original setup cost but the day to day cost is very low. We have email alerts set up on the system and unless all 4 servers go down at once, we will get email notifications on issues. Therefore I only really touch the system when it tells me something is wrong.

Update - Since upgrading to DxEnterprise and removing Melio, maintenance costs in hours are basically nothing. It has been a few months since we have needed to contact support and that was more just a heads-up that we were starting an update from DxConsole to DxEnterprise. We have had no need to contact Support since upgrading.

Unfortunately, you need to license your test environment, as well. We have a test environment purely for DxEnterprise.