There's a newish grocery store in Littleton, called the Littleton Common Market. It's newish because it's been around for a couple of years under different owners. The current store is carrying a good selection of Chinese vegetables and other foods. But the big change is that they are selling baked goods from Yi Soon in Allston, and you can order bbq items (roast duck, roast pork etc.) which are delivered over weekends. I'm not sure where the bbq comes from, but it's bagged in Super 88 bags.
I tried some of the baked treats last Saturday (the only day they come in freshly baked) and they were terrific. Prices seem to be the same as Yi Soon's (around $1.50 - $2 for a bag of cookies, 70c for egg custard tarts, around $1.50 - $2 for large pastries). They had a limited selected when I was there in the afternoon, but they do a lot of business in the morning so they were pretty shopped out. There's an order list so I assume you can place special orders, just as with the bbq items. I plan to order something from the bbq list to see how it compares. Having this available saves me a long drive into Boston.
So far the menus for Yi Soon and the bbq meats are both in Chinese only, and the people in the store that I've met have limited English. I'm going to try to persuade them to translate the menus into English which will help the non-Chinese speakers.