As stated, for a corporate client or a highly polished folio there is nothing like the real thing although you need to understand that these are generally produced by significantly sized agencies who have the scale to employ a photographer / room / lighting / cameras within their studio team, hence it is routine for them and cost effective. You could pal up with a photography studio offering them design in return for mates rates.
However, if you are freelance with limited budget, but pretty handy you can achieve something decent with a camera and Photoshop. Most of my CV presentations are illustrated although I will take a photo initially to help with perspective and shadow. I did first year photogrpahy at Uni and have worked with enough Pro's to get a reasonable base shot with natural light. Couple of examples:
1) Finished Audio CD visual produced before manufacture i.e. it didn't exist to photograph but was required for Amazon.
2) Point of sale concept - again produced before manufacture, later used in a digital CV. Although the illustration is OK I could have done more work on the shadows to be photo-realistic.
3) This one was out of necessity. Although the branding appears light, the actual machine was in pre-build in a dark, grungy engineering unit and my work was to visualise it complete, with the pale grey powder coat paint / dark grey base and logo position - as if it really existed. I toyed with the idea of ghosting a factory location behind the machine (as if in situ) although went for a more graphic, presentation in the end to make it more unique to the brand - the work was for a US audience and it worked, - the company received an order on the basis of this and a short video of the prototype in operation in England.
Hope this helps you on your journey.