Why are part for T4x much more expensive then T2x & T3x

[argy110]

Hi,

Thats the question!

I have a T40 and want to get me a slim second battery. Thats unaffordable! And the same stuff for the others T's seems to be ok?!

Why is that? But ... much more important:

What are good places to get cheap T40 extra euipemnt? (besides Ebay)

Tx, aprociate it,

Ralf