I just ran around to a few Junk yards here in NC and parts are going to cost you at least the minimum purchase as they don't want to be bothered with small stuff. They make their money on the body panels and drive train. For one place it was $20 for a seat bolt cover and a lower steering column shroud. The other was $35 for a cargo package tray and the tiny automatic transmission lockout cover.
Most have their inventory of cars online. But it depends on the yard as to how you can get to them. I was allowed to go with an employee in the yard and point out the stuff I wanted. Luckily it was already removed and loose. But if not, the employee would have to remove.
A seat is easy.
They may not want to do the console...but if it's a slow day...and you're nice and let them know that you know how to get it out, they might take you out to the car and work with you to get it out.
Steering wheel is gonna cost you because of the air bag. But that is something they may have pulled already.
The carpet...I don't think they would pull that for you. If you find a car at a place where you pull your own stuff, then ok, you do it...but they aren't going to spend 3 hours dismantling the interior for a $50 carpet. Most car interiors are open to the air anyways (carpet is gonna be nasty). You can probably get new carpet online. Unless burnt or acid damaged, the carpet should clean up really well. It's tough stuff. You can also sew or glue it back together.
The key to junkyards is to BE NICE and RESPECTFUL. These guys will be really nice if you remember that their stuff is not just "junk" but their livelihood. I always show them every nut and bolt, down to the last washer I picked off the car...and I don't haggle much. Wasting their time is not cool.