Even Though Free Inventions don't bring in any money, itd be useful to have stats for how many are sold, which is the best selling one, cheers, ect for them, as this could be a good way of coming up with prices for inventions, and even a sort of economy, where if an invention is a consistent seller and sells alot for free, then the owner can try pricing it and changing the price to find the best price:profit ratio, maximizing profit.