You can find a list of Cisco partners in NetFlow technology, as well as commercial and freeware software here:
you can try PRTG tool from Paessler to collect netflow data,it gives neat reports and graphs,it is affordable also.
try this link
Many people I know use the product from Arbor http://www.arbornetworks.com/
There are quite a few /fairly/ inexpensive commercial collectors, but it really comes down to what EXACTLY do you want to collect. I'd recommend downloading a trial and seeing what you need, what you like and what you don't need.
I personally use the flow-tools opensource package with various perl plugins to analyze for specifically what I need to collect.
we use ManageEngine's Netflow Analyser (NFA). A new release is due out shortly with greatly-enhanced functionality.
They have a pretty comprehensive suite of other apps as well.