Please forgive me if I come across as being smug, but as a transmission guy, you would not believe how often I hear the very same thing that you have just written.
Tons of money get's invested into the engine and so often there is nothing left for the trans.
Anyway, your question was, can you do the work yourself?
Lots of people that post on this site have successfully rebuilt their own trans and, you can get good support from the trans people that visit this site, as well.
But, if you're gonna beat on it you better go thru it.