Weren't some folks in another thread wondering what bonds were good for?
25 bonds a spin in the fair for something like a cheap buff or Fair Gear (are we 100% sure there's not or will never be a hidden achievement for having all L3 fair gear??? The Fairiest??), or another bond letter to spin again to hit on a 5% xp potion or Inno belt or gear chest.
So we've got confirmation of gear chests and Inno belts dropping.
Here's where the folks that wonder what to use their bonds on have a place for it.
Watch and take notice of the cycle of the prizes in the Fair. They're a bit different from one day to the next. If it's xp you're looking for, wait for the day when the 5% xp potion is a level 2 prize and throw some of those useless (not what I think of them) bonds at hitting it.
If I had to guess, I've gotten about 18% xp gain out of the Fair. No Inno belt, no gear chest, but a ton of buffs that were free. But I've thrown some non-useless bonds to the Fair to get that approx 18% xp gain. Both the bonds and the spins paid off when I hit, but I'm a gambling man.
Not to mention the anywhere from 18-40 bonds rewarded for contributing to it's construction each time. Flip those bonds right back into spins when I see the prize layout structured for what I'm chasing.
A nice dynamic every month or so. Keeps me on my toes and breaks up the monotony. For free prizes that even if I contribute zero to get.