Does this mean just a will? single or married? how much property or accounts involved?
if it is not that complicated you can do it yourself. In my office the minimum is a will, living will, financial and health care power of attorney: for a single person ~ $900. I have no idea if that is reasonable but my clients say it is for the value I add.
practice in California and a fee for a couple with a modest estate (unlikely to be worth more than $1M on their death) usually runs about $2000.00 Bump it up to $2M and it may range between $2500 and as high as $3600 for a trust that provides some good asset and divorce protection for the beneficiary's. But when you get up over $2m the fees can jump up quite sharpely.
It seems that about 30% of my clients initially request only a simple Will. However, very few people leave my office without Powers of Attorney for Health Care and Property too! And many people decide it makes sense to establish a Living (Revocable) Trust too! Why? Because the laws today are not simple and it is most estate planners objectives to offer what makes the most sense for their clients and families - and the circumstances with each family are quite different.
The documents that are commonly done for most estate plans in Illinois (and likely in most states) include: A Health Care Power of Attorney, a Property Power of Attorney, a Last Will and Testament and a Living Trust. Assuming that the client owns a home then a Deed would need to be prepared and recorded to transfer the home into the Living Trust. But, depending on circumstances and the clients' objectives, significant changes can be made to the standard documents. Additionally, other documents may need to be prepared to deal with other circumstances such as Medicaid and Nursing Care issues. It isn't just the documents that you are paying for it is the Good Legal Advice that you are receiving to make it all work!
With that said, fees to do planning differ significantly not only on states but also by county as well as the attorney or law firm doing the work. I would suggest that you look to the website of the National Academy of Elder Law Attorneys (naela.org) to find a qualified attorney in your area. Most charge for an initial consultation a fee of between $100.00 and $300.00. They will then advise you, based on your needs, as to what the full cost of their work will be based on what documents you wish to be prepared.