Hello,
We are a team of software engineers with 6+ years of experience in professional software development.
I assume that what you need is a desktop based application to generate invoices and manage payments. If so, we would be able to create it in Delphi, it would have no external dependencies and would work on all Windows versions, XP and onward. There is also an option of it being multi platform, eg it could also be compiled to run on Mac OSX. The payments and other required data would be stored in a local database, for example SQLite.
If you want a web application instead we can create one as well, in PHP/MySQL.
In any case, creating and printing invoices and reports of any kind as well as a slick and modern looking interface would be no problem to implement.
As for the tracking of account receivables and payables and payments for sales/purchases, this can be done as well but we would have to know the requirements in full detail before we can estimate the amount of work effort required and provide a final price and time frame proposal.
Based on your more detailed description we are also available for creating a small demo for you to test before you accept our proposal.
Let me know if you are interested, we will discuss the details.
Regards,
Filip
CodeStream