My recommendation..
1) EMD - (Exact Match Domain) - If that's available take it. It is a ranking factor regardless of what Matt Cutts video you seen. I know, I have some and they rank with just a few backlinks.
2) If you can buy a domain, that relates to your niche that has a backlink profile in place - It's worth the money.
3) I did it the hard way, making my own brand. But it's a lot of hard work and I would of loved to have a head start, but I didn't know any better at the time. My focus wasn't internet marketing, SEO, etc at the time. I was a developer just putting together a useful site to help people email properly, I didn't have $$ intent. Until the cost of supporting the site started to become an issue.
4) A domain with a good backlink profile - won't be found on expired domains, you'll have to buy them at auction.
5) Expect to pay about 100 per 30-50 unique backlink domains at auction (depending on quality). If it's Keyword domain, toss a few hundred more onto it. Yes, it's worth it - If you're serious and you have the right attitude.
6) If you buy the expired domain and if the original owner did the back-linking, you might be able to go back and easily modify some of the old back-link anchors, to better suit your niche. By recovering the password (If they used email under the domain name)