I have seen a few sets on non branded carbon panels for sale on e-bay in the past but the majority of them don't come with the the arm rest/window switch holders.Siebon are the only makers i've come across that includes these parts.
I fitted a pair of Siebon carbon door cards to my Supra a while back, so i speak from experience when i say they are a total nightmare to fit.It took me 3 days in total to achieve good fitment.As firstly the panels would not fit over the interior door handles, so i had to trim a fair bit off the back of the panels to get them to fit flush on the doors. (Both sides were the same)
And secondly the Siebon panels don't come with pre-cut holes for the window switches to fit into, so you can either cut holes in the panels to fit them or you re-locate the switches elsewhere.Although if you choose to re-locate the swithces you will then have to modify/extend the wiring according to where you re-locate the switches to??
I cut holes in the panels when i fitted mine as i wanted to keep the window switches in the stock position, but this was nerve racking to say the least!!
Personally though, i think they are truly worth considering.Apart from the early hassle of fitting them, the quality of the carbon weave and finish is flawless and end result is stunning.
Prices for Siebon door cards from the US are currently around $1600 delivered, although there is a trader on here who can source these Siebon door cards for you.The last time i checked on here they were around £600 delivered, but that was 12+ months ago!! so they will cost more now for sure.
Hope this helps mate??