I will bid on jobs that I'm sure it would be done at the specified time frame and I'll ask the employer to specifically describe the requirements.
I'm an expert in C/C++ and Java and of course PHP is a joke. I'll write your code in a way to be extensible in the future and readable by other programmers. That's an important factor. If you're already in the business, you know what would happen if you loose your programmer and you have a badly written code in your hands.