As a large company, we first bought the complete BrassRing package, which had various features. Later on, we paid extra for specific features like customer test management. When we integrated with third-party systems, it often came with additional costs. Simple integrations, like posting jobs on LinkedIn or Glassdoor, were free, but if we needed more complex integrations that shared candidate information between different systems, we had to pay extra charges. It is definitely a cost-effective solution. I would rate it a two out of ten in terms of costliness.

IBM currently offer a minimum 10 licenses that generally land at about £35,000/year. Additionally, consulting and implementation (which depend massively on the size and complexity of your organization), can add an additional £20k - £40k to that price; but that's a one-time, one month time frame cost. IBM are also now looking at being able to offer Watson Analytics for general data analytics use (not IBM Kenexa Talent Insights - and thus not necessarily HR-oriented in its approach). Monthly, non-recurring costs are around £100/month without any obligations; but again, this is just using the Watson Analytics capability without the HR wrapping.

I'm not sure about the license cost. We have a yearly subscription.

Kenexa Brassring was fairly priced. However, they recently increased their rates significantly. I believe the pricing was based on licensing and how large the database was. 

Customize as much as you can upfront, as it would be worth it in the long run to have what you need now, instead of waiting or trying to get that later.