As multiple designers will attest, I am more than happy to pay for design work (nothing we have up publicly came from Themeforest or 99designs). But unless your concept absolutely depends on graphical experience --- and look how shitty Pitchfork's site was for years and years and years in the trendiest most superficial demographic imaginable --- graphic designers are a terrible thing to block your project on.

Rather than wrack my brain and carefully come up with a scoping document laying out all the pages and functionality in my next application --- a document that will be out of date exactly one customer meeting after I write it --- I'm just going to point my next designer at a $12 Themeforest theme and say "do this, but way better".

I don't mind that it costs $5-10,000 to get "better than Themeforest", but I do mind losing weeks of release time sweating whether it's time to pull the trigger on a designer and what exactly to have them do.

99designs is a different story. I don't have the designer's moral problem with spec!work but the misgivings people have about quality and IP infringements are based on real issues. I still think it's a good tool, but I can see why some would avoid it.

Avoiding Themeforest though seems crazy.