I don't think it will hurt the price of ore busters too much since it's random unlike last year so people can't tell people where to find them. The price might lower a little in the next week but I think it will jump back up quickly.
Does it matter though? This event is not about money. It's about having fun and Aikar/staff saying thanks to all its members.
It's a drop in the bucket. Don't worry about it, ore buster prices will probably drop for a bit, but they'll come back up.
Having been through the previous event (300k) I can rest assure you that the impact on the economy will be minimal. Of course, if you wish to gain some rupees from all this then your best strategy would be to either sell off your stuff now (in an auction for example) or... store them and wait it out a few weeks. A majority of players will try to go for the quick & easy bucks so they'll dump their stuff in auctions 'en messe' which will obviously have some impact on the bids which people will make. Why bid 30k if the other auction is still sitting at 22k and hey: new auction just appeared with a 5k start (all fictional examples, but based on stuff which I've seen happening last time). So if you want to make the most money out of this then its best to be patient.
Yep. A temporary spike in supply will cause a drop in prices, especially for less available items like some of the promos. It will pass very soon after the event ends.