Even if their budget isn't the highest in the world, this is still feasible. Quadrotor technology has come pretty far in the last few years, so it will cost less to do this than you might think. Sure, it might be an utter failure when it comes to usage by customers, but it is feasible to get it started.
And to those saying it's inefficient, I have three points for you:
1. It's not inefficient, way less pollution and power consumption than a truck (and yes, I know it can only deliver one package at a time while the truck can deliver many, but overall, I'd have to guess that the truck is still less efficient.
2. No pilots are required, meaning that it doesn't cost much to run this service once it's going. Repairs/servicing, replacement parts (both of which take place on trucks as well), and people doing data entry are the only real costs involved. Battery charging is fairly minimal; while it does add up over time, the extra price on the electricity bill would be almost negligable - most certainly less than the cost of gas for the same mileage.
3. This service is provided for the convenience of the customer, and to make extra bucks when people use the service. Regardless of how efficient or inefficient it may be, it provides a desirable outcome for each party.
