There probably are filters or plugins for the likes of Adobe After Effects, Adobe Premiere etc to take out the fish eye effect but I wouldn't like to rely on them bailing me out. The video has to be shot correctly at the production stage and as you are a professional in real estate, presentation is everything. A Mini DV camcorder would be fine for what you are looking to do and even make a DVD for clients and the quality would still be very high. The 4000 dollars you quote would be better spent on a few items rather than just a camcorder, that at the end of the day will only be used to put videos on your website. That means a decent Mini DV camcorder, some editing software, a tape head cleaner, a tripod is a MUST HAVE (no handheld shots) and of course your wide angle lens, you may end up spending a few hundred on it alone.

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Better than a poke in the eye with a pointy stick any day...