All sellers are always located in 1 central location in all cities in India.
Like Chadni Chowk in Kolkata, SP Road in Bangalore, CTC in Secunderabad, Richtie Street in Chennai, Lamington Road in Mumbai & Nehru Place in Delhi. And 95% of Distributors will have offices in the above specified places as well.
These sellers located in those places like for ex: Arun Computers in CTC get from different distributors located in India & sometimes import parts directly from overseas vendors to make more money. If I go to ditributors they either will ask how many pieces do we need or say higher prices than sellers. If any illeterate buyer goes to buy from sellers they loot you by selling sub-standard parts at high prices as I was such a buyer in early 2000's to 2008. I bought 3 times from 2000,2005,2008 from Bhumika Computers in CTC and they looted me by selling frontech, zebronics, circle likewise parts for a whole PC for 50k each time. After 2012 I started going to Arun Computers and bought for 1lac and Mr.Raghu MD gave me best prices and even sourced me parts which took a few days.
So there are some notable distributors in India for PC components like: Ingram Micro India, Redington, Savex Technologies, Compuage Infocom, RP Tech India, Supertron Electronics, Tech Data India, Inflow Technologies, Brightstar Telecommunications India & iValue InfoSolutions.
The sellers who have shops in the above specified central locations of all major cities source their components from the above ditributors. Some import from Taiwan directly.
Regarding how much each seller makes take for example: AMD Ryzen 5 7600. This processor they get for around 15k from the distributors because they get it in bulk. The distributors give parts on credit to the sellers and every month end it is paid. The price of 7600 starts from 17k and goes to 19k offline while 17-18k online. Because brick & mortar stores need to buy more permits than selling from a warehouse/office. Example was I bought a Asus Phone in 2015 but went to the office of the seller who was selling in snapdeal at that time. So he gave me good price. Office was on 1st floor while packing and shipping was in ground floor via different couriers.
When ever I go to buy parts I always go to a few sellers like Arun Computers, Shwetha Computers, PL Computers only. These sellers always give at best prices than the remaining 100 or so shops in CTC, Secunderabad. These 3 also make money but dont loot the customers and will give genuine answers or suggestions. So I always have their MD's, Salesmen Phone numbers with me and I call them from home before going for a purchase. If the said parts arent available they will source it after certain date and inform me. So always 1 should be a good seller with genuine advices given to any buyer who to buy from them.
The initial Capital should be around 50lacs at the least and go upwards. Since all distributors will provide you components for credit running the business will not be an issue.
Normally some sellers such as Arun Computers do servicing of computers, laptops, printers, networking for the local engineering colleges & IT companies which will pay them monthly or annually and will have agreements accordingly. This is another source of income for the sellers