Modify osCommerce Contrib - Adjust prices

This modification automatically adjusts prices for products given changes in exchange rates. The idea is to automatically calculate the current estimated cost (based on vendor/manufacturer pricing and discounts) and add the appropriate margin to get a current (US Dollar in our case) price. [Our osCommerce version uses the extra products contribution, and through that includes a field for the list (i.e., manufacturer suggested) price in the home currency.] The basic calculation is as follows: (home list price) // (field defined in Product Extra Fields times (1 - discount) // (new field we need to add to manufacturer table) times (exchange rate) // (from currencies table -- based on the currency specified in "home currency") The above gives an estimated cost. We then use the commercial margin to get an updated price. Here's an example of how the calculation should work, based on current information in our database: Harry Potter e a Câmera Secreta (Harry Potter and the Chamber of Secrets) Cover Price (in Brazilian Reais - BRL) $36.50 Discount from Brazilian Publisher (Rocco) 40% Current Exchange Rate (BRL $0.4714) Calculated Buy price (36.50 x (1-40%) x 0.4714) $10.32366 Margin for Brazilian Publisher (Rocco) 110% Calculated Sell price ($10.32366 x (1+110%)) 21.68 Round up to nearest quarter $21.75 Here's the details of what we need: This could be done as a mod of the Quick Updates contribution but I'm open to getting a similar result in another way. 1. Add following fields to database: * to manufacturers table: discount * to manufacturers table: margin 2. Modify Quick Updates (or get this another way) to show/modify home list price (from Product Extra Fields), home currency (from Product Extra Fields), discount (new field from Manufacturers table), estimated cost (calculated), margin (new field from Manufacturers table), suggested price (auto-fill into editable price field, and show separately), and the difference (net and percent) between current sell price and calculated price. Ideally should be able to sort list based on most fields. Please allow user to limit the titles displayed/included in reports to: * all titles * those of a particular manufacturer * those in a particular category With nearly 12,000 products, I need both a way to update prices universally and a way to update selected products. Limiting listings by manufacturer and category will be very helpful. 3. Modify Quick Updates admin fields to manage the above fields added to the report. Each of the above fields should be something user can choose to not display, display, or display and allow edit. 4. Modify manufacturer's admin page ([login to view URL]) to display and allow edits to new manufacturer's fields. 5. Modify product edit page ([login to view URL]) to show the discount, estimated cost, margin and suggested price -- suggested price should be like the current Products Price (Gross): field -- something that is recalculated when the user changes the home list price or home currency fields. Ideally, I need to update the prices monthly -- and certainly whenever the exchange rate changes by more than a minimum percentage (say 5%). It is also possible that the Buy price could change because the manufacturer/publisher changes the discount given. Of course, changes to the list (i.e., manufacturer's suggested price) would also lead to a recalcuation. But while it is certainly possible to have changes in these items kick off an update, I'd prefer to have it be a manual process -- so that I can verify what happens. Since I believe this can be done principally as a modification to the Quick Updates contribution, I've put a modest budget for the project. If you disagree about the amount of work that this will take, please tell me!! You can simply bid what you think, and post a note to me on the board telling me why this should take more money.