Cab to either best buy or target. Traffic should be your focus as both are close but you can take a long time either going or returning to airport pending am or pm rush. What time of day?

Only train options is to green acres or valley stream but a pain as must take AirTrain to Jamaica and change to valley stream bound train. Schedule will make this a challenge and will have to walk a little bit. But, you do have three retailer target, Walmart and BB.
Another alternative is about 30 mins which is AirTrain to Jamaica and take subway to queens plaza/center. this stinks because you will need to transfer to two subway lines express to local.

Not sure how much time you have and how much you wish to spend on transport to store. Queens center offers about 1/2 mile of stores but must walk from one store to another.

If you have limited time and may deal with rush hour traffic and not require to browse the laptops. You might consider a pickup at store option - buy it online and simple go to the pickup counter while the taxi/cab waits outside to return you to airport.