You're right that flat packs would be great, but they'd be heavy so cost of shipping would be high. That's the rub. You can have a local cabinetmaker cut pieces for you much cheaper and make your own flat pack kits that way.Which sevens are you planning? You mentioned an 18" woofer, so maybe the Audiophile Series seven π-18 would suit you. The Stage, Pro and Audiophile series cabinets are the same, so there's an easy upgrade path built-in. Then again, the cost of woofers is enough for the Omega 18's that you probably wouldn't want to toss them to upgrade to a Magnum 18HO or a JBL 2241. Might be better to get what you ultimately want right from the start.