Create Specific Virtuemart 2.x Report Plugin

I need a report plugin created for Virtuemart 2.x compatible with Joomla 2.5. Report needs to measure a specific product's sale numbers vs. current stock over a specified amount of time (date range - select start and end). MUST work for stockable child items as most of the products are such. So it would tell me that Product A has sold 50 units over the date range I specify and there's currently 21 in stock. Doesn't need to be too fancy - just functional. Would prefer it to be a plugin...but if there's a cheaper way to do it as a hack I'm open to that too... Happy bidding!