Wills can be expensive. My firm is on the low side for fees, I've done one will where we only charged $150 but many of the ones I've done are $400+. However, probating a home done will often turns into an expensive nightmare. Each state has different requirements (for example, Texas requires 2 witness and a notary and the testator and witness sign in 2 places).
If you plan a simple will, borrow a copy of your mom's and look at the layout. Check to see what it seems to require and go from there. For witnesses, do not use a family member, you need people who will not benefit under the terms of the will.
If you really want to punish yourself, go online and check out your state statutes for probating a will. Check to see what they require and write your will accordingly.
Of course
I recommend an attorney. I need people to provide fees so I can get paid.