Best Buy’s alliance with Samsung is getting even deeper. The Richfield, Minn.-based electronics retailer already has two store-within-a-store spaces dedicated to Samsung products — one for TVs and the other for smartphones and mobile devices. Now, in some stores, it will add a Samsung-branded space for appliances. The “Samsung Open House,” a roughly 20-by-20-foot area, was installed in Best Buy’s Maple Grove and Maplewood stores, as well as one in the Chicago area, in early June. It will roll out the mini-shop to about 200 more locations by the end of the year.