We are not in domain business, but I regularly buy good names when I see them fit for some of my future ideas. Sometimes I manage to get inexpesive domains, sometimes I buy domains for several thousands USD. Eventually you will spend at least several thousands per month on your PR and SEO activities, so having paying once for a good name one time is not that big loss, especially on rebranding stage.
I highly prefer .com as seo guys say it matters, but there are some other domains which you can play with, like .io , .QA etc. if you want some fresh name and want to save on .com.