If you are looking start in product photography, keep your expectation realistic. Go to SMALL companies to start with, Forget corporate for now, as your skills get better, your portfolio grows, and network expands, that type of work will come. Rather than wasting your time with mailing expensive material, maximize your exposure by going where small business connect, your local chamber of commerce or business organization. For the amount you spend on marketing collateral, postage and the time to get the names, addresses and putting it all together, you could take a handful of potential contact you meet through the chamber of commerce to lunch. It is said your net worth is your network (not my quote but I wish it was) and it is so true.
You can land well paying work in this area by being a better provider of services to the millions of SMALL business. I have one client that I offered a great price to shoot every product in their line, now the come back as packaging changes and product lines expand to update their image library. They stay with me because I take care of them, not because I am the cheapest (but the quality of work has to be top notch to get top price.) I also deliver the images ready to use for any application. One version for print, one for large view web and one thumbnail web optimized and ready for use.
Keep in mind that small product photography falls into two categories, simple white seamless, and creative (which many times showcases the benefits more than the actual product.) Think of it from the end user perspective, why would this image entice me to purchase this product. Look at LOTS of catalogs and critique the photography, dissect how it is lit and shot and be sure to ask yourself why it was shot like that.
You CAN get work in this field if you work at getting your foot in the door.