Magnetic Card Swipe readers are a perfect solution for swiped transactions at low volume retail location, at special events, and wholesale building supply companies. If the location is likely to have a lot of debit card transactions (see past history) then a cost benefit analysis is needed to determine whether a solution with pinpad would be a better alternative.
Assuming it has already been determined that the merchant does not need a debit pinpad, then magnetic strip (magstrip) credit card readers are an excellent solution. They hook up to your computer so you can get the benefit of most retail interchange rate, provided the software it interacts with a) can capture all the data needed and b) will pass all the data needed to the processing company and c) the payment processor will accept all the data needed. While it seems simple, in reality not all gateways pass through all data, regardless of whether it’s been captured. So if just the card number and expiration is passed through, but the best interchange rate for the type of card presented also needs another field, the transaction would be downgraded to a higher rate.
Mag tek is a well known reliable brand and prices start at about $75.