Yeah the only other ones I see are about 220 to 260, I could suggest sending an email to one of the smaller hydro shops online and asking about a discount for buying so many at once.
The place I go to in person to buy stuff usually rounds things evenly like most headshops would when you buy a new piece. I don't see why they wouldnt do such a nice sized online order in the same fashion. I can't garauntee this method would work, but hey its worth a shot.
Other than that, it looks like you'll have to make some from home depot materials, or you can check craigslist or something.