You guys must be in a pretty pricey area. Im my area (Western Pennsylvania) $200/month gets you great pasture board. Right now, I pay $200 for a stall but that's with a $25 discount. That's hay and feed twice a day and 24/7 turn out. They only really come in to eat and to be groomed.
OP, I think your best bet is to try to find a way to sell them or to just accept your fate that you are across the world and are unable to control the situation at home. I don't say that with any kind of nastiness. If you are that worried about them, have them moved but expect to pay more.