Availability in a hardware store will depend on the store.

A typical multimeter consists of an ohmmeter, voltmeter, and ammeter. Some have more functions as well. When measuring amps, most are limited to 10Amp maximum though. I would recommend a digital multimeter with auto-ranging capabilities.

When you start wanting to measure current draw for servos or other electronics which consume current in short bursts, you will need a unit which can "capture" the information to memory, and then display it after the event is over.