I have to admit that about 10 years ago, everybody will resort to customized software. Means you will hire software vendors, spell out your requirements and get the ball rolling.. Then you have to go through testing stage, user acceptance test and etc.
But for now, I would say that you can probably get an accounting system suite, that will do the job for you. This is because, a typical accounting suite will have the following modules.
- Sales Module
- Stock Module
- Payment Module
- Sales Order
- Delivery Order
- Cash Sale
- Debit Note
- Credit Note
- Cancel Sales Order
- Delivery Return
If you need customization, get those software suites which can cater for customization. One software suite which I know of is AutoCount Accounting.
The more famous brand is UBS-Software by SAGE. But UBS is not known to be able to be customized heavily.
The other one I can think of is SQL Account.
Still thinking of customizing another software ? I don't really recommend that if you are SME.