get the DSLR
One of the nicest things about digital photography is the ability to easily edit your photos. There is a program (who's name I forget, but it was reviewed about two years ago in PC Mag) that has "profiles" for a large number of lenses and automatically corrects the distortion (NB: (i) all lenses have some sort of distortion; and (ii) interchangable lenses require a DSLR). Just about any photo editing program will allow you to "stitch" together multiple photos into a compound image and most will correct lens distortion to a reasonable degree (without the special-purpose software mentioned above).
My suggestion, spend the bucks to get a DSLR (everyone likes Cannon). While there is not a linear relationship between $ spent and quality of outcome (easily this board's slogan) there is a reasonable correlation. This is your job, after all. This allows you to get new lenses to suit your needs as time goes by. If you get at least six megapixels, it will suit your needs for a long time. If you get one with more, it will allow you to blow up smaller parts of your photos without loosing as much picture quality (notice how the distortion is more pronounced towards the edges of the fisheye photo). Once you buy a SLR "kit" with a lens, you can always upgrade the body and keep your investment in lenses. Also, while it's bigger than a point and shoot, you can detach the lens from the body and put "lenscaps" on the body and each end of the lens so you can fit it easily into a briefcase. Finally, busting out the SLR may impress your clients (sellers) more than some dinky point-and-shoot ("it's important to get the best photographs possible," you tell them).
My $0.02