How exactly did van helsing cost more than revenge of the sith?

I would say traveling. I don't know if Van Helling was shot on location, but they definitely went to a lot of different places to set up. Miami Vice was shot in Miami, Haiti, and Havanna. Plus to rent a large ship and get other people to clear the water. That stuff is expensive - not to mention Moby's fee.

Well, maybe it was because most of the effects for the Episode films were done in house by George Lucas at ILM (Industrial Light and Magic), Lucas' Effects company. Remember, Most films are farmed out to different industry companies to be made for Studios. Effects, Makeup, Post Production, etc... Lucas is self sufficient. Lucasfilm Ltd. Is a studio in and of itself, he can produce and make his own films, Skywalker Ranch, his compund out in California has sound stages and Effects houses and everything most Studio Lots have on them, so i would imagine being able to do most of the expensive things himself, actually does limit cost expenditures.