Or the other bulb to get would be a Repti-sun 10.0 flouresant tube bulb. However, if you go that route you have to use a calcium supplement that includes D3. If you use the Megaray you won't have to use the calcium with D3 - you would want to be sure to use the calcium supplement that doesn't include D3. If you got the Megaray I am assuming (having never used them) that you wouldn't have to change your fixture.
I'm not sure on the whole "take the lizard outside" thing. Part of the viv is heat regulation for the dragon, he can move in and out of the heat. I suppose if you were to supply the same conditions outside for the dragon, you could leave him outside. I wouldn't do it, but that's just because I really worry about him being healthy and safe. I think it would also be harder to regulate the amount of UVB they receive. I think it would be a great idea until you can get a good bulb, but that I wouldn't rely on it. Of course, other people may have a different point of view.