In reply to Connor Nunns:
They're heavily discounted all over the world, from what I've seen. Half-price here in Australia. Maybe just not a popular size in today's market.
They don't look to hold 90 litres, but it's sometimes hard to say. They're meant to carry a high volume but not-heavy weight, - tent, big sleeping bag, high-altitude down clothing etc - relatively short periods of time. Osprey makes other packs for bigger loads and longer trips.