First thing's first - Don't ask strangers on the internet for tax advice - ask your accountant.  

In saying that I have two pieces of advice.  Depending on scale - spend the money and use Xero or MYOB etc to do your reconciliation.  Put everything through a single bank account linked to your software, so you just login, you'll see your transactions and you can allocate them to various cost centres, attach receipts and so on.

Two - purchases of inventory are NOT AN EXPENSE.  You do not get to claim purchases of inventory as a tax deduction or an expense.  The only time you can claim the inventory cost as an expense is when you sell the item - Cost of Goods Sold.   Unsold inventory is an asset, it sits on your balance sheet.  It is not an expense.  You may end the year thinking you've made a modest profit because you've been investing in inventory, but that asset value will be deemed as profit and you'll be taxed on it.