I have palyed around with it a little in years past. I used Alum and Salt for the tanning agent. If properly done you can get a fairly good hide, in a natural white color. It is a lot of work though and you will never have a hide like the tannery can give you. Ya it costs a few bucks to get a hide done, the last elk I had done was $90. Seems something like $60 for a deer. I haven't sent any in for two years.
I would suggest sending them out and working a few extra hours at your job to pay for it. You can earn the money in a lot less time than you will have in the hide.
Of course if you really want the experience, there are Chrome tan kits available that are better than the Alum and Salt method.
Here is the url of a good tannery:
http://www.foxvalleyleather.com/