As the others have correctly pointed out, a great domain name will always bring additional traffic your way. However, it’s impossible to predict how many of those visitors would in fact be interested in what your site has to offer. Some will certainly stay for the content, but that additional bump is often not worth the cost of an expensive domain.
If the domain name that interests you is accessible, I say go for it. If not, then you may want to go for a cheaper one. In the long-term, content, SEO, and backlinks will do more for your site than a strong domain name ever will.
