There are time when keeping a venomoid can be useful but having one for personal enjoyment is not one of them. The only reason I have ever seen for keeping a voided snake is to use it in educational shows where the speaker will be hands on, it allows the speaker to talk without focusing so much on the animal and keeps the audience safer. Of course... the audience should never know that it is a venomoid because we really don't need people thinking they can have all sorts of venomous snakes because they can just get them "de-venomed"... then we end up with all sorts of inaccurate back yard hack jobs and...whole long chain event of bad things.....
also, as someone else mentioned... venomoid inc. is the only company that is doing it properly and legally (that i know of). There are others who CAN do it properly... but not legally... which means they are more likely to screw it up due to lack of proper tools.
There are many things in your original post that worry me with you owning anything even remotely venomous. First...you called it a "pet". These are not "pets". That term is already one that I am not fond of anyways but it should certainly never be used in conjunction with something like a venomous snake. Second, you seem to be looking at the cool factor, said it yourself that it would be a cool pet to have. You cannot get into something like that just because it is cool. If you want to work with dangerous animals you should have a real passion about it.... well that goes for any animal really. because the cool factor wears off a little while after you have to start cleaning and caring for something and the high you get from telling someone about your awesome new pet wanes down till it no longer outweighs the responsibility factor and you become careless and lazy with the animal.
Now, I don't mean to say that this is exactly what you are doing, It does not appear that you really want to mess with the hole venomous thing in the first place but you are a little vague so it's best to get you to analyze yourself now and figure out exactly what you are going for before you get caught in the wrong direction and in over your head.
So as far as cobra substitutes go, a pissy hognose is probably your best bet. Saw a luecy texas rat put on a pretty entertaining threat display once, neck flattened laterally, mouth open, the whole deal. I believe some Asian rat snake species do that as well.