Shaun, I could be wrong here, but I think your profit figures refer to mark-up.
If so the gross margin on your bike sales (on return) was about 13% after discount, your other goods 33.3% at retail price.
Apart from frames most of my purchases were 40% to 50% off the retail price for quantities or direct from manufacturer.
I lost count of the number of times I was offered discounts like 33% plus 10% which is 40% not 43%.
In those days we had purchase tax on complete bikes, but not on components.