First, congrats on your decision and I hope you love the bike.
You can get a far wider range of anything for motorcycles in the US than you can in India from what I've seen, at a far higher levels of quality and commensurate price. (unless you need a cheap part for your 120 Honda/Hero or whatever...)
You can even get wheels as ugly as the ones you posted.
Given the post Orange County Choppers hangover this country's in, it's not gonna be hard.
Quick google shows: http://www.wixwheels.com/motorcyclewheelcatalog.pdf as an example, and I'm sure that's nothing compared to what you could find/spend.
"Custom chopper wheels" "motorcycle alloy wheels" etc will get you more results than you want. I for one, however, would discourage the purchase of wheels that potentially cost a large portion of your bike's worth, especially when they only change the aesthetics rather than improve the bike's functionality for you.
To each his own, however...certainly my soon-to-be Enfield project is not going to be to everyone's taste. Just remember that an Enfield in America is by comparison an oddball, small, classic, and interesting motorcycle, not the fire-breathing King of the Road cruiser bike it's often considered in India.
Edit to add: one practical consideration is that alloy custom cruiser wheels (and matching tires) in the US are more likely to be found in fatter widths than used stock on the Enfield, so consider what will actually fit inside the relatively narrow frame/fork.