Not sure if you are after any of the actual framework, rams, pump etc and I haven't actually replaced one yet however I have recently ordered the following parts (actually in a complete kit) from Mustangs Plus:
171.66 CONVERTIBLE TOP WHITE
72.21 WINDOW CVT REAR PLASTIC
37.36 PAD KIT CONVERTIBLE TOP 65-73
25.46 WELL LINER BLACK CVT BLACK
62.01 BOOT CVT TOP WHITE
It will be delivered in a few weeks time and for under $400.00 (I think that's it summed up) it seemed okay...
Now I don't know how much of a sh1t-fight I am going to have actually installing it - I have read that it can be a "bit difficult" but I am always up for a challenge.