You can order them from several sources but the cheapest way to to measure the size you can use and go to the nearest auto salvage yard. You can wire it with a relay or buy a temp. controled switch that is adjustable and it will start whenever the temp gets where you like it. each item should cost about $30 I have a extra fan but you are a little too far away.
Works well in my warmed over 350 so should handle yours.
