The amount of detail you want in your rolling stock and what you are willing to pay will affect your purchasing decisions. You can buy rolling stock with separately applied detail or cars with the details molded on. The more detail you want, often the more you will pay for a car. Also, there are operating cars available with moving parts and sometimes are even powered (like dump cars, etc.). If you are doing a night scene on your layout, you will want lighted cars (these tend to be passenger cars and cabooses). These can be more fun and realistic on your layout but will cost more than non-operating cars.
Most often, the auto parts you will require will be quite common, and are probably parts like bumpers, brake pads, seatbelts, wiper blades, and so forth. In recent times, it used to be that no matter what was required the car would be taken to the local mechanic. Now a lot of people are doing their own work on their cars and there is an increased demand for specialized parts. Some of the items people are now changing which they didn't in the past are parts that are required to convert to lower emissions levels. Fancy wheels, specialized wiper blades and even specialty headlight covers are some of the other common specialty items.
2) The junk yard. While you might think you are above visiting a denver junk yards, are you above saving a lot of money? Probably not. anaheim pick a part inventory in at the local junk yard might save you a lot of money compared to a new air filter. And, even better, this ties directly into point #1. A friend of my, Robert, needed an auto part so he looked online and found a junk yard. The junk yard shipped him a part that was almost new and he couldn't have been happier. Just cause an air filter is used, doesn't mean it's very used!
The next step for many RC hobbyists is the Nitro car. Nitro cars are driven by miniature engines which run on a mixture of nitromethane and lubricating oil. These cars are very fast with a fast acceleration. They can reach and maintain higher speeds than electric cars, whose batteries are constantly running down which means less power for speed.
Truthfully, used car parts will save you money. Obviously it is cheaper than buying brand new car parts, but do you think you'll be getting the same quality? That is something you should be concerned about. Fortunately, most auto parts recyclers will offer a warranty with their parts. They also have a full database which makes it much easier, and quicker to locate parts than at a dealership. Even if they don't have the part you need, they can get it to you pretty quickly.
You can also look on the Internet because of the presence of auto parts that are made for performance and speed. These places usually have competitive pricing but you may not like the shipping rates that are with these online auto parts stores. This is the downside to ordering on the Internet as well as any other time that you may end up ordering your auto parts for your race car.