Should I get Genesis 30 or wait until the mini-dungeon event starts again?

I strongly suggest getting an item which is impossible to get outside of the event. I only found out about the Maple Chair yesterday, but that's what I am shooting for. I understand it's just a chair; but it is probably not going to be available again. Mesos will get you valuable stuff, but even something like a 15 attack workglove is something you can eventually get by doing APQ, merchanting, etc. To the best of my knowledge, to get a Gen 30 from event you need to do the event map for a long time. You might not get a chance to get the other things if you're shooting for it.

Of course, if you want mesos, you're really best off with Genesis 30 because it's valuable. I have to caution you that the prices of that book (as well as other Horntail skillbooks) is steadily DEFLATING. TT30, Gen30, Bliz30, Berserk30 and MW20 are rare and valuable, but a lot of people are getting them by participating in Horntail. With each Khainian that passes one, the demand decreases and so does the price. People say that clerics are common, but meso-rich lvl 130 Bishops are NOT common. To the best of my knowledge the books in question are still valuable as they are because there is cross-server trading going on. If they are not that needed in Khaini, you server change a mule with it and a bunch of stuff to Scania and sell it for Scania prices.

Hope this helps.