While this appears to be the logical first choice to most, borrowing from a bank does have its drawbacks and can often limit the overall amount of credit you can obtain. This is caused by the method of securing loans that banks use as in many cases they will attach collateral security to everything you and your company owns to loan an amount of money. These are the dreaded GSAs or General Security Agreements and personal guarantees that allow them to take any or all assets you may have to pay off a loan in case of default. If you have confidence that you can pay back the loan this is not a problem, except that other financiers may not like the idea that if something went wrong, the bank gets theirs and they may get nothing. Although this looks unfair, it is reasonable to the bank.
Banks are in business to loan money and receive money back as payment.
They don't want the item you purchased, they would much rather take easily disposable assets like new inventory, cash, accounts receivable and your house. Product suppliers, while they too would like to be paid in cash, will often give you short-term credit as, being in the same business, your items of inventory have some value to them. However, they have the same problems as retail dealers, they are not banks and usually don't have the resources to give long-term financing to everyone, even if they wanted to. Besides, product suppliers love cash and some will give additional discounts to get it quicker. DInvestors are wonderful if you can find one but are really expensive if you do actually make the profits you promised them.