Grimbergen Cuvee Blanche is in the style of a Belgian Witbeer aka "White Beer". There are are countless similar beers that are widely available.
The archetype for the style is named Hoegaarden. The creator of Hoegaarden, Peter Celis, created another beer in the same style named Celis White. In the U.S., the most widely available example of this style is Blue Moon Belgian Wheat.
Belgian Wit / Belgian Wheat style of beer has gained a lot of popularity in recent years and is an exceptionally easy style to find at any well-stocked bottle shop or craft beer bar in the US. Simply ask for that style and something similar to Grimbergen Blanche should be available.