Gigya is NOT free, those API keys are supposed to be for evaluation only. Social Login Pro is likely to be worthless if you aren't a millionaire. Here is an email I just got from Gigya.
In terms of price, many factors are taken into consideration when creating a quote including number of sites, pageviews, specific plugins, professional service, and even length of the agreement that you put in place with us. I can give you a general range that our social suite on the low end can start around 20k USD per year and range up to 200k. This includes a one time implementation and an annual license fee. With every contract, you are also given a dedicated client success manager who will assist with design and implementation as well as maintenance. It's really a set it and forget it technology.
Does this fit within your budget for the project?
All the best,
Tel: 650-353-7230 | Fax: 650-324-2776www.gigya.com
Yeah...$20,000 USD per year + installation fees to use a login service.