if you can't afford to pay someone to do the cover for you, then you might agree to exchange services with them in exchange for their design work..e.g. provide backlinks to their site or do some promotion work for them etc.
If i was going to design a cover i would probably buy some stock photos of some business man etc and then just whack a few big titles across the cover and that would be it. just "borrow" from the style of other books in your niche. maybe download some fancy free fonts. there are lots available for free.