"Lowest Price for Profit"
If I may...
Your cost should not come into the equation at this time. You need to set your selling price based on the value of the item to the buyer and market conditions.
If an item generally sells online for $25 and the market is relatively strong with sales by your competitors in that price range on a regular basis, your selling price needs to be in the $22-$25 range. Whatever your cost is, that factor is irrelevant in setting up your selling price.
If you paid $30 for it and need to make a profit after adding your fees, etc... You will never succeed.
If you paid $5 for it, count your blessings and sell it the the $22-$25 range just the same. Too often we find sellers on eBay (and elsewhere) selling at prices way below market because they were fortunate to acquire the item at a low cost. They are wasting their potential profit. All sellers need those "fat profit" items from time to time to pay for things that do not work out.
If you have a large quantity of the same item, then "turnover" comes into account. How often do you want to sell an item and how many will the market absorb in a given period of time. Once again, that has nothing to do with your cost or expenses.
To do your calculations properly, first determine the appropriate selling price, then deduct your cost of the item, then your selling expenses (eBay listing fees, FVF, store fees if applicable, PayPal fees, conversion fees, shipping subsidy if applicable, etc.).
The FVF rate depends on the type of products you sell (different categories attract different rates), how you sell (FVF on auction is different from fixed price) and whether you have a store or not (different fee schedules apply).
In general terms, if you sell low priced items (under $5) you should consider your eBay/PayPal fees to be in the neighbourhood of 20%/30%.
The higher the selling price, the lower the percentage paid in fees.
A $3 item at fixed price will cost only $0.05 to list if you have a Premium store (49.95 month). If you list 1,000 items a month, that works out to $0.05 per listing.
FVF on $3 may average 11% or $0.33 (rate varies by category).
The fee on PayPal will average 6% including conversion fee plus $0.30 per transaction for a total of $0.48.
All above assumes your shipping costs are fully recovered by charging the buyer whatever your shipping and packaging costs are including a - unmentioned - handling fee to cover fees)
So on a $3 item you have $0.10 listing and store, $0.33 FVF and $0.48 PayPal for a total of $0.91 or 30%.
Now, repeat the same set of calculations using $6 selling price, $10 selling price and $25 selling price.
Once you have the basic calculations taken care of, you need to add an estimate for your "sell thru" rate. For example, if it takes you two and half months to sell an item (turnover of 5 times a year), you need to add $0.10 listing fees (2 extra months at $0.05). If a large percentage of your business goes overseas you need to factor the PayPal 1% cross border fee somewhere, etc... etc...
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HE WHO BUYS RIGHT.... SELLS RIGHT !
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Good Luck.
