By way of context, human transcriptions cost about $1 to $1.50 per [EDIT: minute] --which is what I use for my podcasts. Accuracy is extremely good, especially if you flag obscure terms when you submit.
ADDED: Machine transcriptions are pretty good for a lot of things such as search and quickly skimming content. But if you want something that people can read as an alternative to listening to the podcast, you pretty much have to use human transcription or budget a bunch of time to fix up.