NetQoS built Allocate to do just that. It handled chargeback based on utilization, but allowed granular control over how much each type of traffic cost etc, etc. Too bad it was discontinued.
There are a couple MySQL queries that could easily give you what you're looking for. It would be better than using a sample of NFA files through the NAST tool.
For example:
select routername, count(*) from agents_all_view where enabled='Y' group by routername;
Will give you a list of routers with the count of interfaces enabled for reporting on that router.
select routername, enabled, count(*) from agents_all_view group by routername, enabled order by routername asc, enabled desc;
Will give you a breakdown of how many interfaces on the router are enabled vs. disabled.
select b.description, count(*)
from agents_all_view a, harvesters b
where a.HarvesterAddress = b.address
group by b.description
order by b.description asc;
Will give you a breakdown per harvester.
If one of these doesn't get you started, give some more details about exactly what you need and I'll see if I can craft a query for you.
To run any of these queries locally on the box, execute
mysql -P 3308 -e "sql_statement"
at the command prompt, where sql_statement is the query to run. You can also connect directly from your service using ODBC or the MySQL DB driver.