Free plan is available with features from the "Mini" plan but the "Page Views" are limited to 500/month and catalog size should not exceed 500 products.
Get started with a free plan that allows you to create N active pages every month. An active page is one that has active Tagalys API's and shows products when loaded. Tagalys will keep active the most recent N pages, where N, is the number of active pages permitted by your plan. Details on pricing can be found here
The cool thing about the free plan is for retailers who are getting started, you can have as many as 20,000 products and the pricing only kicks in when you cross M number of page views, as defined in the pricing plan found at http://www.tagalys.com/e-commerce-merchandising-pricing