As I've just said in another post I would be suspicious of buying something out of work/sold from the field as I would wonder if there has been a problem with the horse. There are people who will take the chance and pick up a cheap horse from the field and get themselves a nice horse but I think you are narrowing your market by not getting him/her into work. If you don't have the time or facilites why not consider a sales livery somewhere, you may find the balance in what you can sell him/her ridden to what you will get from the field and be better off.
I did have in sales livery but ended up spending £2500 with no sale and to be fair it was worng time of year but horse is only worth £2000 so don't want to end up spending too much on him