I'd love to have this service at home, so I'm (selfishly) hoping Instacart becomes hugely successful! That said, I can't help but wonder whether the company will find a business model with sustainable economics. A lot of really smart people have tried and failed to accomplish this sort of thing before. For example, Amazon invested $60 million in Kozmo.com back in the late 90's, and they couldn't make it work. (Kozmo.…
It'd work something like this:
You go online.
You want to buy a new A/V receiver
You find the one you want on Amazon at 9 am
Amazon then asks you where you live
Amazon taps into a database of willing stores that might carry the product. Most big-box stores have web-based inventory checks, so syncing their inventory with Amazon's system would (hopefully) be easier. Amazon offers the service to more specialized outfits; Smaller stores would get support in integrating the inventory system. Amazon would have to make a deal with these stores to make this work.
Using a partnership with UPS/FedEx/et.al., Amazon figures out which locations are still due for visits from a logistics company. Most make residential shipments as the last part of the day.
Amazon tells the store, "A customer requested this receiver, please put it in box size A1 and hand it to the UPS dude with this shipping label."
Amazon pays the retailer below retail, but above cost. The retailer takes it because they want the business; Amazon recoups because same-day shipping is a premium.
Box goes on the truck, truck comes to your house.
Voila, new item by EOD same day.