I see nothing "outrageously excessive. " with this pricing, It is a comercial product and prices at a very reasonable price.
Have a look at the cost of a Single SIP channel licence for a Mitel system.
A lot of time and money was spent on R&D for this and that is not cheap or free.
How much does a e1 cost to connect to a Asterisk ? Thats right just the cost of a card $200 - $300 with Mitel you are looking at $1000+ for a card and $1000+ for the licence for it.
If you dont wanat to pay that, Then there are cheaper alternatives and soon There will be SIP trunks from Skype, But they wont be free.