For someone who loves to travel and cook, the prospect of helping my friend Christina, fellow alum of Columbia University’s graduate journalism school and resident of Stockholm, prepare for her 40th birthday party could not have been more tantalizing. So, while my husband Sean bounced around Europe, attending business meetings, I recently hung out in Stockholm for 9 days, shopping, cooking, and sampling the fruits of our kitchen labors. Because I am accustomed to cheap American food prices, I found grocery shopping in Stockholm shocking. A quart of milk ran about $4. A pint of raspberries went for anywhere from $7 to $15. A single bottle of 3.5% ABV beer, the only kind sold at markets, cost at least $3. Wine? I paid twice the amount that I do in NY for a bottle of Penfolds Koonunga Hill Shiraz-Cabernet. No wonder everyone asks out-of-country guests to pack a healthy stash of alcohol in their suitcases. Forget that extra sweater. Bring more rum! Vibrant outdoor markets, such as the one held behind the Hotorgshallen food hall, did offer bargains. There I stocked up on bundles of fragrant fresh mint for Friday night’s mojitos. At less than $1 …