Carpet is about $135 from LRS for just the front these days. More if you want Mass back. I have tallied up the total cost to redo the one pictured and it is pretty scary!
Although there are some costly parts that were not necessary but I wanted (fiberglass hood ($500), Fiberglass hatch($250 used), Cervini's Cobra body kit ($1200 on sale), Paint ($1200 with primer/base/clear) ) I am about 8K total invested in the car, and I bought whatever I could on sale and used to try and control it. There are just so many parts that can nickel and dime you to death.
Granted, the car will be nice when it is done, but I could have bought a nice running car with that kind of money. Building your own car is cool because you get the sense of pride and you get EXACTLY what you want, but it costs more and it costs more of your time. I'm about 3 years so far and I really just want to be done and drive!
Good luck with your car!