Does anyone ever purchase more than 250gm worth of discs?

If not, I would probably use the promotional postage discount function, then charge $2.60 per CD to a maximum of $6.45, which would result in $5.20 being charged for 2 discs (and I would post two separately, because it's cheaper than posting together), then 3+ would be charged at $6.45 - but not more than that, so if someone ever purchased enough discs to exceed 250 grams, you could lose a bit on postage.