I regularly have prospective clients call and not really know if they want to spend the money for a professional photographer. In most cases they do need to hire a professional, but occasionally I am able to help someone with only sound advice.
In general, if you think you might need a professional, you have already realized that a snapshot is not going to properly communicate your professionalism. This is certainly more than the usual "I need a better camera" statement that everyone seems to think is the most important factor in photography. Understanding lighting and perspective are two important factors in portraying an image.
If someone needs a large number of similar images of different products that will utilize the same lighting - for example, someone who sells many similar small products on ebay -- they will often be better off shooting in-house with a little bit of training or a lot of trial and error. There are a number of inexpensive lighting kits available at etailers or ebay. I recommend this approach if the products are unique and not very expensive. In this case, hiring a professional is cost prohibitive.
In most cases, hiring a professional that makes your product, service, or business look incredible. A professional has the correct equipment, experience, and training to make the most of your image. Your professional photographer should have a portfolio that impresses you. It may not be important that your photographer's portfolio is shooting your exact type of business, but it is important that the lighting and illustrative effect of their images creates the type of impact for which you are looking.
It's also important to remember that the expense of professional photography is an important part of your marketing budget. And, always remember that although a photographer's day rate may seem quite high, there is typically a lot more time that goes into the shoot that non-photographers may not realize. There is a lot of maintenance and cleaning of equipment directly related to your shoot, pre-planning the shoot and deciding on necessary equipment for the location, and the biggest factor is post-processing. Post-processing is the act of editing the images for final publication. This is time consuming and difficult work.
Often, clients will easily spend $10k on a website and resist $1000 in photography fees. This is a big mistake because the photos are as important to overall impact as the design of the site.
