Give M&R your serial and they will give you a market value estimate. They typically seem a little high (obviously).
We've sold a few presses through Don Fenno over the last few years (just get the money before it leaves the building).
Online I've seen them from around 10k - 16k, depends on how fast you want to sell.
I'd say go with a broker, you'll get a few thousand less but I think it is worth not having to hassle with finding a buyer unless you can find one locally and make them move the press themselves.
Also, M&R will sometimes take an old press on trade in, so that would be a 3rd option but you have to handle freight to get it to IL.