As far as the headliner, you can get it from any of the big names and they range from $120 to $150. That is for the entire kit which includes the board (now ABS plastic instead of cardboard), faom backing, and headliner material. You can just buy the headliner material for about $50 and re-use your old board, but you also have to buy new foam backing for about $6. You also need to buy the adhesive for the putting it all together which is about another $4. So, you can save money by re-using your board, but it also takes time to clean off the old board and get it prepped in order for the new stuff to adhere properly. So it comes down to time vs money. I have done it both ways and found it is better just to buy the whole kit because it takes about 3 to 4 hours to do it all. So, I spend $60 more dollars to have the whole kit, but it saves me 4 hours.
The carpet is easy to replace. You have four bolts in each of the seats to take out, four screws to remove the shift bezel on the console, then 6 more bolts and screws to remove the center console from the car (two bolts up front, two screws that hold the console box in, then two more screws that hold down the center console under the console box). You then also have 4 screws in each sill plate to remove and that is about it. You do have to loosen some screws that hold the rear quarter panel and lower front kick panel and toe guard in, but you don't have to remove those. You can just loosen them to be able to slide the carpet underneath them to install.