"Unless your needs are simple—say, you want to leave your entire estate to your spouse—none of the will-writing products is likely to entirely meet your needs. And in some cases, the other documents aren’t specific enough or contain language that could lead to an unintended result."
When a client has an attorney prepare a set of estate planning documents, the client is paying for more than an attorney to correctly insert the names in the document. He is also receiving the attorney's years of wisdom and experience in administering estates, knowledge of state specific laws, and general knowledge of human interactions through the estate process.
My conclusion? The difference between the attorney's fee and the cost of a DIY package is small in comparison to the cost of a mistake or overlooking an issue in a self-prepared will.