Chrysler Repair: 2001 Plymouth Neon - P0601 code, plymouth neon, last legs

Question
Hi there,
I read an answer here for a 2001 Cirrus that came back with this error code as well.  The answer said that a used controller could be purchased off a car of the same year/engine...something like that.  How does one do that?  And how does one know if the one being purchased is any good?

Also, what should I expect to pay for one of these used controllers vs. a new one?  And also, if I manage to purchase a used one, how much can I expect to pay the dealer to do the final programming on it, or could I take it to someone OTHER than a dealer?

My car has just over 103000 on it.  I realize it's probably on its last legs.  But I really can't afford to buy another vehicle right now.  I also can't see how to justify the $700-$900 "rough estimate" the dealer gave me over the phone today, PLUS the $97 for actual diagnostics.  Really frustrated here and would love some advice.  I truly know nothing about cars.

Thanks in advance.

~Laura

Answer
most cases U will get what U pay for now that being said  9 times out of 10 a used computer can not be reprogrammed to the new car. The programing is the vin number to which the car uses the vin to know some of the stuff it has on it. Second thing  if u have a gray key  U will not be able to use a used computer any way  the alarm system is not transferable. 3rd issue. If u get a used computer u might get one that had an alarm system in it and it will not work for yours for the fact u may not have one  and so one and so forth.
Price for a computer can be 300 to 700.