The prices are going back due to bitcoin miners going out of business. If you're trying to mine bitcoins, DON'T! Just buy a few when the next crash comes, sell them when you want to, buy more, etc. This is how I do it now.
They are not going down at all and MtGox has no effect on Bitcoin. They were merely an exchange. Granted, a lot of people used it but it has nothing to do with the coin itself.