I believe vendors / retailers get final say, but there is a relationship to maintain so typically manufacturers have decent pull.Vendors raise pricing on their own sometimes, too.
For example Tide (a huge brand) has more leverage on pricing at Target / Walmart vs. a lesser brand.
Gigabyte is a large brand so I wouldn't be surprised if that is genuinely the new retail price.
Also it makes sense with all the price increases since launch. They just keep going up. And it might go up again early April.