We (Braintree) are priced competitively. We may look higher than others because we don't use any pricing trickery ( http://bit.ly/cUyJTa ) and bundle gateway services. We created a checklist for merchants to help them avoid getting duped http://bit.ly/9W57Pw .
I should clarify. Braintree is perfectly competitive as long as you're handling some volume (20K/mo or so), and are willing to roll your gateway and merchant account into one provider. For smaller ventures, not so much.
It's actually between 2-5k per month, depending on average ticket. For merchants looking to maintain volumes less than that for the long term, other providers will cost less in monthly fees (but may have a higher total cost when including other items such as pci compliance, recurring solutions, etc.).