$10,000 Cheat
There is a cheat code available that will allow you to access $10,000. Select the "Options" screen to enter your cheat code. Enter in %%$3/" in the cheat code field. This will give you $10,000 to start the game with. It's a nice amount of money if you are wanting to get a good start but not be too greedy. It will definitely help out with buying newer cars and customizations.
$15,000 Cheat
There is also a cheat code available to access $15,000. This is probably the better option since it is a larger amount of money. Go to the cheat code field and enter in S1D3KICK in all caps. This will give you $15,000 to start the game. This is the most amount of money you can get with a cheat code. A nice choice for this code if you are looking to stocking up your fancy car collection quickly.
Expensive Cars
To obtain some of the high dollar cars, enter the code 0;5M2; to receive the Lexus IS F car. Type in -KJ3=E to get the Lotus Elise car. To get the Nissan 240SX put in the code ?P:COL. And use the code !2ODBJ: to get the Volkswagen R32 car. Use the code citwoxq53f to get the Chevy Camaro Concept and the code qlcukc4bqm to get the Dodge Charger. You will get a Ford Mustang GT with the code i3kxodepfc and a Mitsubishi Lancer Evolution with the code 2<?P;G. To obtain the Pontiac GTO use the code d5dviyrlgn. You can also get a nice Porsche 911 Turbo with the code >8P:I;. The signature Need For Speed car is available with the code NeedForSpeedShelbyTerlingua.