Peugeot 406 driver’s seat defective

Hello, After a long time I report again. This time the existence of my 406 is at stake. In May the TÜV is due and my driver’s seat is broken. I.e., a cross-section of the seat frame is broken, so that the seat now shakes quite strongly (swivel chair). My workshop man says that the part can not be welded so easily, because it does not allow the material. Furthermore, the seat must be completely disassembled (because of the airbag). In addition, the conversion of the seat. Together with further repairs, which are due before the TÜV (brakes, track rod heads, exhaust…) the costs exceed the residual value of the vehicle. But I found in a large online auction house used seats, which seem quite inexpensive. The problem is that these seats are not suitable for any kind of use. What do you think, can I install an electric driver’s seat in my Peugeot, which does not have any electric seats from the house? Do all cables already lie there, so that I only need to connect them, or are there other conditions missing? If this is not possible, the seats are all the same, so that I can possibly use the frame and the rest of my “old” seat from an electr. seat? And how expensive would a seat be? Is there a change?