Not sure where the location of the shop would be but you would need to sell at least 350 cups a day, and that will be impossible for at least the first 3 years for a small privately owned coffee shop. You can't start out charging as much as Starbucks, in fact you can never charge as much as Starbucks if you expect to get sales! Then you have to factor in a lot of other expenses like insurance, equipment, etc, do you get a loan for the equipment? if so that's another monthly payment. Then you have to have the cash to buy the coffee, creamer, etc.
Starbucks sells an average of 700 cups a day, you'll be lucky if you do 350. You can't expect to get some of that 700 cups over to you, people are foolishly dead set on going to Starbucks even though their coffee is watered down!
Being right next door to a Starbucks is not a good location, with that close of a proximity you'll be lucky to sell 150 cups a day!! That means you will sink.
The other location will only have 1/4 to 1/3 the traffic, so figure on 1/4 to 1/3 the number of cups of coffee you'll sell.
You need to get a realtor that knows about business traffic, and locations, and try to find a better location than the last one for as cheap a month as possible.
The other word of warning. Most commercial rental properties the owners will suck you in for a low monthly rent, then about 3 to 5 years go by and to renew the lease it goes up by at least double, why? Because they know they got you, they know that most people are not going to quit the location to go find another cheaper place and basically start all over again. A lot of businesses have gone bankrupt due to the rent going up too high and the business owner could not make enough income to pay the rent and all the other bills.