We found Lithium to be priced very competitively vs principle competitors in 2007 when we selected them as our strategic platform. I think the expenses have scaled fairly well with our particular use case and we have added additional features over time. I believe those features will hold even more value as their usage ramps up.
If someone just wanted to do one thing, perhaps blog, I don't know that I would say this was the best way to go. But, if someone had an eye to build out a community that could be integrated with other aspects of their web site, and they wanted to engage customers or partners in multiple ways and across multiple languages, and wanted to integrate into CRM and prominent social networks like twitter, facebook, and wanted a rich set of platform analytics and the opportunity to integrate with a social listening platform to better understand the qualitative aspects of the discussions (topics & sentiment), then this is a good road to start down.