Disney Event Photography offers a $310 engagement/anniversary/just married photo shoot in street clothes at the resorts or at Epcot, and anyone can do it. You don't have to have been married at WDW. However, they won't do it at the other parks anymore because they can't get in before the parks open and they say there are too many other people in the shots.
You can also do the full-on bridal portrait session inside any park *except* the MK even if you weren't married at WDW. That's $650, and you can wear formal attire.
Disney's PhotoPass also offers private photography sessions for $50-$100, but they are all just at the resorts too. But I've heard of couples getting an in-park PhotoPass person to follow them around to various attractions and take their picture, so maybe you could do it that way.