There are several artists that I talked to that were willing to do an ebook cover in the 80 dollar range--licensing a cover at a yearly rate was cheaper in some cases. Sure, these aren't your big-name famous cover-art authors, but there's a lot of talent out there!!!! I found art I liked and names from
www.AnthologyBuilder.com by studying the covers there.
Same with editing. I've done editing work and been paid by the word, by the document and so on. It doesn't have to cost 5k. Marketing? I'd like to think that a trad publisher would spend that much on me! There are smaller PR firms that will do basic PR for 500 dollar packages--but most what comes in small packages are things you can do yourself.
Any large business (such as a trad publisher) is going to attract and have to pay for more expensive artwork/editors/PR and so on. It's part of their success. The little guy can do a pretty good job, if the little guy is willing to--on a much smaller budget!