I just hired a designer from Dribbble to do logo, illustration and homepage. $400 logo, $900 for illustration and $1200 for homepage design. The work was good, but not perfect. Luckily I am an experienced web designer so I am able to work with what I got. The main problem was that the designer I hired was really good at illustrations, but not as experienced with web design. The price worked for me because I used 99 designs as a bench mark for cost, found a designer I liked on Dribbble and his quote was within a couple of hundred dollars of 99 designs.
edit: grammar