I would disagree about trying a grocery store or big box phal. They've often been through so much abuse in shipping and hanging around the store, that they are pretty stressed even if they still look fine. I would spend a few more dollars and buy a phal from an orchid greenhouse, you don't have to get the biggest and most expensive one.
If you buy a bix box phal and it fails in your office, you won't know whether to blame the office or the big box store.