When you say "many companies" are saying you need a store, are you meaning the suppliers for the product you are wanting to sell?
If so, then there really isn't a whole lot you can do about that as every company has the right to limit who they sell their product to. I am guessing that they are trying to limit the selling of their items at wholesale prices to someone that may just be looking for a way to get equipment at a cheap price. If you work out of your home, who says you are going to be buying a lot of their product? You don't have as high of an investment as a brick-and-morter store does so you the legitimacy is harder to determine.
The requirement to have a physical shop is becoming more popular as there is so much saturation online with just web-only shops selling products that a distributor may want to have more control over their product.
I'd talk to them about it and see if there is a minimum order that perhaps could allow you to sell out of your house (thus showing a commitment)? Aside from that, you may just need to determine if the business is worth it to open a shop or find a different type of business that doesn't require a brick-and-mortar location.