Not to question your information, but the build kit page doesn't specify that the kits are 1/8". The separate cogs listed on the crankset/bottom bracket/cog page are lsited as 3/32". Are you certain the kit is 1/8"? If you're buying the whole kit, it doesn't matter, but you may want to call IRO if you haven't done so already.

Aside from the fact that the ring is on the inside (this isn't an issue for anyone but me, I guess, but it has been an aesthetic thorn in my side for some time as far as building up a fixie is concerned- that and fear of pedal strike even with 165s is what eventually made me buy a track frame, which will arrive Tuesday), it sounds like a great deal. You're not going to get anywhere close to that price with any track-specific 1/8" setup. The BB may be a weak link (long-term), but you can always buy a higher-end model. 68 x 110 and 107 are no problem to find.

The site states that the crank with a 107 or 110 (seems you'd have to pick one or the other) will give you the correct chainline (42mm).

I'm going to order some wheels from IRO soon. How are yours?