We are a rural team in North Idaho and are having a difficult time finding an ARA recycler in our area that will sell us a seat motor. If we source a seat motor from a non ARA source would that motor be legal for competition? 
Did it come from a previous FRC KOP? If not, then no, per [R48I].
Note that the rule restricts the source from which the motor is obtained, rather than the more ordinary restriction by part number.
Maybe you can find a team in another area willing to acquire a legal motor for you? Or perhaps an ARA member that will ship parts to you?