Thanks for taking the time to consider me.
Because you said at the beginning that you wanted a simple site, I can't imagine charging you more than the 500 (GBP) I've bid would be fair. You haven't listed too much in the way of requirements. I'd like to ask you this mainly to stimulate your thoughts a bit: Do you want the booking system to be a simple button on the web page that, when clicked prompts the user for their name, location, destination, departure and arrival times, and payment method? Then that information would be transmitted to the company.
Or did you have something more sophisticated in mind? For example, a credit card payment can be made and verified via interfacing with systems like PayPal. Or you taxi company may have their own method of taking credit card payments. Would you like additional fields for the customer? Perhaps a text field for any additional instructions like: "I'll be waiting outside on the northeast corner."? Or a field for an email to be sent to them?
Do you want to have some type of availability checking, to ensure that, given a specific time and date, you will have a car for them?
If you want to add more functionality to it that, of course, requires more programming on my part. And of course, I'd like to be reimbursed more for the work.
I would be very happy to work for you, though. And I hope I've demonstrated this with my questions.
Thanks again for considering me.
And kind regards,
Jim (Fourth Ring Consulting)