POS software

Hello,

I am looking for a ready-made POS (Point of Sale) software that is already developed. I do not want custom development from scratch.

My requirements:
• Complete POS system (billing, products, customers, reports)
• Works on Windows / Web / Android (mention what you prefer)
• Already developed and tested
• Basic setup and installation support
• Source code preferred
• One-time purchase
Important:
• My budget is low, so please contact me only if you already have a ready-made POS
• I am not looking for expensive enterprise solutions
• Demo screenshots or demo access is required before purchase