Mobile app (Cross-platform) for data-entry of prices, local storage, and sync data with

This will be a simple app for a user to make entries of prices and descriptions on the go on a form. It will be a simple table format, though with multiple "sheets". There will be a certain number of fixed categories. For each category, there will be a spreadsheet/table listing with 6 columns, and a limited (but not fixed) number of rows. The amounts will subtract from a total, so some calculation involved. A bit more than a simple "notepad", but very simple for a database. This app will not connect to the web or a cloud service. All data must saved be on local storage on the device. It will be synced bi-directionally with a desktop Java application when the phone is plugged into a computer. (That application is not part of this job.) The data on the device must be saved in a way that a desktop application can read and then clear the data (either in database format such as MySQL or some other format like XML), so app is "empty" again. We need a cross-platform app: iPhone and Android. Also preferably Windows Phone. Each will go to it's platform's store. You may use whatever toolkit that allows you to write the app once, such as PhoneGap or moSync. In other words, write once, compile 3 times, not write 3 times. More details will be provided when the bid is accepted. Some conditions: You agree to non-disclosure of proprietary information. You agree to turn over the source code, and that we will be the owners of it. We will be setting milestones on this project. Some questions: 1. What toolkit or language would you use to create a cross-platform mobile app? 2. To you, what is the best, or simplest, way to store data on a mobile device so it can be read by other applications connecting to the device? 3. Have you created forms like this before?