The policy used to arbitrate domain name disputes (UDRP or Uniform Domain Name Dispute Resolution Policy) dictates that building a company on a site like bufferapp.com doesn't give that company the right to the corresponding .com. (buffer.com) Attempting to sue to get the name is called "reverse domain name hijacking" and the arbitration committee is very very skeptical of those types of request.
That being said, the price of the .com will track the perceived value of your company. It would be an awful waste to have to use a significant percentage of some round of funding to buy a domain name. Also, it seems like a significant percentage of your type-in traffic would be lost to the buffer.com. Even 10% of your type in traffic is probably worth the $xx,xxx you will pay for a decent .com name.
The arguments against paying for a decent .com seem weak.
Case in point: http://www.thedomains.com/2012/06/16/rick-schwartz-wins-the-...
That being said, the price of the .com will track the perceived value of your company. It would be an awful waste to have to use a significant percentage of some round of funding to buy a domain name. Also, it seems like a significant percentage of your type-in traffic would be lost to the buffer.com. Even 10% of your type in traffic is probably worth the $xx,xxx you will pay for a decent .com name.
The arguments against paying for a decent .com seem weak.