I have just given a try to ReachStream and the approach they are using is simple, neat and efficient.
I understand the database will be growing over time but as it is right now it already offers a decent amount of data and it is qualitative data.
Shout out to the team for continuously populating and verifying and cleansing the data.
Stupid simple but useful is the possibility to narrow the search using the NIC code
And the best is that Tiers 2 offers unlimited contact views on the web interface + 10,000 contacts export which is a great allowance to be secured before they reduce it :-)