mrswee,
Er... I have to say upfront that there is no offence intended to my comments below:
But the way you go about doing your sprees and advertising your spree blog make it seem like you are a professional spree organiser. Most of the spree organisers here charge between 20 - 50 cents per order for each mummy not per item to cover materials for postage.
So if you charge 50 cents per item, if a mummy orders 5 items, she'll be paying $2.50 for handling? If the total no. of items for the spree is 30 items, you'll be taking total of $15 for the spree.
There is no right and wrong about charging handling but I'm not sure whether this is the forum for you to do so because some mummies here feel very strongly about such things, especially about fixing exchange rate much higher than the actual rate (which by the way, the exchange rate now has fallen to 1.43 and you are fixing at 1.54, so the gains from exchange rate is potentially $20 for a $400 spree) and having to pay more for handling.
Not too sure what the moderators' stand is on this, but if I'm not wrong, generally you are making profit (whether outright charging a percentage, or through subtle means of fixing high exchange rate or handling charges) from organising sprees, then you should be organising the sprees in the Bulk Purchase thread where you'll have to pay a fee.
As to advertising your spree blog, you may have to check with the moderators on whether this is allowed.