Sunfire 2000 Keyless entry faillure

My sunfire 2000 keyless entry system has started to fail. First I could not open the trunk and the driver's door. The passager door would still open on the second command, and I could still lock all doors. I narowed the problem down to the Delphi Module BCM/RFA 09388219. Here are my questions:
Is this module expensive?
If I change it, do I need to also change all my present keyless remotes?
Any tips on how to get this done?
Regards
Amande

so you have changed the battery in remote and it is still crapping out ?. the remotes/key fob from dealer are around $100.00 if I remember correctly. Parts man at local Gm shop said to check at scrap yards for correct remote ,but then again that`s a crap shoot whether you get a good one if you can find one . other than that check e-bay

Thank you for the suggestion, but my remotes are OK, it is the reciever that has the problem. The BCM/RFA 09388219. It is under the dash near the driver's feet. That is the box that I need to replace.
Regards,
Amande

ok so now I`m curious as to how you determined that it is in fact the receiver/module that is failing ?

Basic wire tracing technique.
First, I noticed that when a command to open the passenger’s door was made, a relay (under the dash) on he passenger’s side was activated. I identified the feed wire (a light brown wire) for this relay. I found out that this wire came from the driver’s side.
Second, I did the same with the trunk solenoid wire (the solenoid that pop the trunk open). This wire (a black with two white stripes) also came from the passenger’s side.
Both of these wires ended up on one of the connector of the BCM unit. I then unpluged the connector from the unit and selectively applied +12 Volts on each of he connector’s wire. I could pop the trunk, lock all doors, unlock the driver’s side door, ect. I now knew that the BCM unit was defective.
I opened the unit and found that it was a multi-layer printed circuit board. Part of the circuit seems like a tuned circuit. There was also 3 solid state relays on the board. Because of the surface type mounting of the components, it is close to impossible to repair these in the field, so I needed to replace the unit.
So here are my questions:
How much does one of these unit cost on the used market?
When one replaces the BCM unit, do you have to change the remote as well, or can the new nit be reprogrammed to use the existing transmitters?
Regards

not to say you are not right about the BCM.. but i had the same symptoms with my 2000 Cavalier z24. It was the FOB that was bad.. i bought a new one from ebay for $25 and had A gm tech reprogramme it to my BCM and its worked great since then.

I tried to change the battery on my old FOB with no luck.. the FOB's dont last too long i guess. I would try getting a new FOB first if i were you.

This may still be a cause, but the strange thing is that both FOB that came with the car are acting up the same way at the same time ???
Regards
Amande