say if I buy in bulk an item, and then sell them on individually (planning on doing it on ebay), do I have to pay taxes on the difference? and if so, is it capital gains tax or does another tax apply?
If, as it appears, you are trading in buying and selling goods then income tax/prsi/levies on the profit after expenses is what would apply. Bear in mind that VAT may apply if you exceed the relevant thresholds.