This is good advice, don't get me wrong (I read the article), but you don't absolutely have to have a pro photo. What you do need is a good, clear headshot. Advice like yours is necessary because I've seen a lot of really bad, unprofessional LI photos:
1/ Don't use your Facebook profile photo
2/ Don't use anything blurry: photo should be well lit and clear
3/ Don't use a photo that isn't a headshot—make sure your face is clearly visible and smiling
4/ Don't use anything where you're engaging in unprofessional behaviour
http://www.diyphotography.net/take-professional-linkedin-pro...
Read all the way through, as he points out that it is not the equipment that matters, its the setup with the reflectors, which can easily be improvised...