Pete
I've taken a look at eNom's pricing and I can't see any increases however I know they have altered their cart and there is a checkbox to "Add POP Email to these domains". This is automatically ticked, so unless you remove this it will add $9.95 to each domain.
I just tried this with a dummy order and managed to add 2 of these to my one domain, adding an extra $18.90 to the order.
Personally, I hate to see any cart automatically selecting additional items in the checkout and frankly I think it is a very underhand way of generating additional sales. I will be sending a complaint to them about this - it may not do any good (unless they receive huge volumes of complaints) but I'll feel better