Hi asantha,
We tried registering a TM on our own, wanted to save the money, it is as simple as filling in the form and paying the lodgement fee.
After we submitted 4 applications for a term/industry with no real competition, all 4 were applications failed, I had a short attention span and moved onto other interests.
Later talking to an IP Lawyer, we were told lots of self registered applications fail.
I strongly suggest using a lawyer!
Although I have never used CooperMills, they have a great reputation and have been very active in the community for a while.