I looked into it a bit more, and the $41.25 was for an antenna assembly of some sort. I searched through the parts to find an amplifier and sure enough, it's right here for $1875.00.

AMPLIFIER. Audio. Speakers, Amplifier, and Related Items. CHRYSLER CROSSFIRE (2004 - 2008) # 05189332AA, 05104860AA, 05136097AA

It shows that the part fits all years of the crossfire, so I think that's the proof I needed. I'll probably go ahead and try this amp I found on ebay and hope it works. It's a ninth of the cost of the one above, so I figure it's worth a shot.