A computer Application which will help me run my Used Electronics Business

I run a secondhand electronics dealership in Nairobi, Kenya. We're currently in the middle of an expansion of workforce and I need a program that will systematize our most common transactions. Those are: 1. Basic Inventory Management (What items bought, sold, any cost of good, etc.) 2. Generate and keep track of quotes for customers who wish to sell their items, using factors such as market value of the item, condition, color, and storage (to be input by the employee) to determine value. 3. Customer queries report (the program should have distinct fields for identifying what customer tried to sell what product and should be able to categorize them as per the name of customer, date posted, brand of electronic, condition, contact info, etc. 4. Tracking weary/faulty devices from inventory that require repair work. 5. repair service tracker based on repair done, device serial, date, customer info, etc.