Build an Online Store

We are a manufacturing ready mixed concrete that deliver final product of cement and other concrete mixed to construction sites. [login to view URL] We need an online ordering form so that customers/clients can place order directly online without calling us. For some idea about ordering idea please see: [login to view URL] Basically we need to ask from clients that: 1) What type of mix do they want? (type or quality of product) 2) How many cubic yard of concrete do they want? (quantity or amount) 3) Location, time, and date 4) other special requests - like will it require pump longer than 200 feet from truck to actual location, etc. On back end of our site we need to check to verify if the location is doable for us. We will need to be able to verify if the client's location is within around X-miles from the distributing concrete plants. We also need to verify that if the time and date of the request is available for us to do, so if there are too many requests at such period then we need to block it or mark as Unavailable. Also we need to have a dynamic pricing system so that the price will increase or decrease according to the demand of that time frame. For example if the cost at 8:00 AM on Friday is $200/cubic-yard, but there are high demand for that time and day then the price will increase 5% then 10% then higher depend on how many additional orders are requested for that period. The price will keep increase until the we cannot handle that anymore then it will be Unavailable. We want to set the preference of price in excel spreadsheet in Google Doc so we can drive clients into certain time/day block that is most efficient to us. We will update the spreadsheet constantly, and the site need to be able scan the information merge it into online ordering form. Once we are thru all that it will be standard check out cart. It can figure out tax rate for client location, after a certain time there will be charge for canceling, etc.