In advertising, you do not score any points by doing it yourself.
When advertising, you are not pleasing yourself, nor are you talking to your existing customers. Rather you are talking to your rivals customers. People who have already looked at your marketing and rejected it in favour of another's.
This is why it is often for the best to seek outside help and professional guidance, if you cannot afford to go the expense of hiring a commercial advertising agency.
The aim is to get a dispassionate outside view of your business. From people who are not invested in your business as either staff or customer. People who can look at your business with fresh eyes and as a potential new customer.
In advertising, the impression counts as much as the message you are promoting. The more it looks like you have invested, shows the confidence that you have in your business.
In short, if you don't have the confidence to invest in your business, why should anyone else?
How much does it cost to advertise? Ask instead how much will it cost if you do not.
Good advertising pays for itself... Not least that you can currently claim it all back from your tax and that there may be grants and loans available.