Samples depends on the size of your business. If a supplier believes you're going to shift ยฃ1000's in stock, then you'll get free samples and probably some marketing collateral. However, some of the bigger comanies actually charge you to carry their brand. One I know of will charge a retailer ยฃ6K to carry their product, so you can imagine how much you've got to sell to get that back. But they do provide displays and product training and some consider that a good deal to carry a market leading brand.
However, the best was for a sole trader to samples is to visit trade shows. The are many startup looking for retailers to take their brand, and will give samples, usually by post after the show.
HTH,
Myarka.