I don't know if you can get it cheap locally, but McAuslen produces a very good Oatmeal Stout wich pretty much any online kit from a respectable vendor will be able to approximate decently. My first batch was the Festa Brew Double Oatmeal Stout and altough it is different, being that it's not a clone, it is still phenomenal.
If you pick a Guinness clone, be aware it will be different from the Guinness you get on tap or in the cans, unless you have a Nitro capabilities. But it will still be goob beer. Most dry stouts are only pale malt, flaked barley and roasted barley, with the proportions or the omission of flaked barley being the variables.