You can buy Will kits in most stationary stores. However I used to be a paralegal and have done up a whole lot of Wills for people, and can tell you that there is no substitute for going to a lawyer and having done there.
There are clauses that you may not be aware of, and if you want your Will followed and to hold up in court if it's contested, it's better to get it professionally done.
Also, don't forget to make provisions for your pets
And it's best to not use the names of your pets because chances are you will out live the pets that you currently have and will have different pets when you die. If you have named specific pets in your Will, the pets that you do have are not covered. I'd suggest wording along the lines of "Any pets that I may have". And indicate a monthly amount for food and medical care for the life of the pets. Make sure that you have stated that when that pet dies the allotted money is to revert back to the Estate and be disposed of in accordance to your wishes either divided up between your heirs or given to a charity that you have named.
I don't know how much it is to draw up a Will at law firm, but back when I worked at one it was usually between $75 and $250.00. It depended on the complexity of it.