Q: What are the main aspects to consider when using multi-pack items?
A: Some aspects to consider are:
Vendor Tax: If you do have to pay vendor tax... if 1 of the item costs $10 for example, then you would pay sales tax on the $10. If you do a multi-pack of 3 (or N) and you're purchasing 3 (or N) of the item from the supplier, you wouldn't be paying sales tax on $10 only anymore. You'd pay sales tax based on $30 (3 of the item). So it would be correct to triple vendor tax in this case.
Pack Quantity: Likewise, your selling fees are always going to be based on the selling price of the item. If you're selling 3 (or N) of the item, your selling price goes up, and therefore, the amount that you pay for fees goes up.
Supplier Shipping: The only thing that wouldn't necessarily need to be tripled would be your shipping. If the supplier won't charge you shipping because let's say they have a free shipping threshold and buying 3 (or N) of the item puts you over that limit so you wouldn't have to pay shipping. In that case, when doing your formula (using the formula wizard on the item), you would set Include Supplier Shipping in Calculations to No, which would keep the vendor_shipping variable from being in your formula. Then you'd enclose the entire formula with ( ) and put *3 (or N) at the end.
Example:
( ((min(max((vendor_price-(0-0.00001))*100000, 0), 1)*min(max(((99999999-0.00001)-vendor_price)*100000, 0), 1))*(((vendor_price)*(7/100+1)+(((vendor_price)*(7/100+1)*10/100+0)+0+abs(((vendor_price)*(7/100+1)*10/100+0)-0))/2+0.3)/((100-0-2.9)/100))) )*3
Or, if it's a situation where you will pay the shipping but will only have to pay for it once, then you could set Include Supplier Shipping in calculations to No as described above and then enclose the whole formula (including the newly added parentheses and *3) with another set of parentheses ( ) and put +vendor_shipping at the end or you could indicate a fixed shipping amount (For example +5.99) or whatever the combined shipping amount would be.
Example:
( ( ((min(max((vendor_price-(0-0.00001))*100000, 0), 1)*min(max(((99999999-0.00001)-vendor_price)*100000, 0), 1))*(((vendor_price)*(7/100+1)+(((vendor_price)*(7/100+1)*10/100+0)+0+abs(((vendor_price)*(7/100+1)*10/100+0)-0))/2+0.3)/((100-0-2.9)/100))) )*3 ) +vendor_shipping
There are lots of factors and it really depends on the items and what the user intends to do.