design a simple crm form / system that can pull data from google docs and post transactions into a spreadsheet

I require a cloud-based system (I'm thinking google forms or similar) that users in various regions can access and securely input customer data as well as transaction details that can post to a central spreadsheet (either in google docs or dropbox). Not such a complicated task, except for one thing (otherwise I could do it myself using Jotform or google forms). The form needs to have pre-populated pricing data that is pulled from a spreadsheet, the product type and quantity is then chosen by the user and the form needs to calculate a total based on 1. the user's qty input and 2. the pre-populated pricing data. I know this can be done, I've already got an Edit Grid spreadsheet working inside a Jotform which can be manipulated by the user in this way but the data is fixed and would need to be updated manually (not an option), google spreadsheets don't seem to have this functionality (I can only seem to get them to display in HTML, not actually accept data). Whereas the google spreadsheet actually pulls the real-time data I need to be able to use for the pricing calculations (through the =importdata function) which I can't seem to do with the Edit Grid. I'm hoping that there is some sort of workaround that can be done using a google widget, otherwise we'll have to build something from scratch. I'm obviously trying to keep costs fairly low here, but at the end of the day need something that works properly too.