The Spotmeter V is a great meter and like said earlier the button cells are easy to find. Stay away from the older Pentax spotmeters. With some the batteries are hard to find and the earliest ones are impossible to find.
I shoot large format and the Pentax spotmeters are so easy to use with the zone system. I own a Spotmeter V and two digital Pentax spotmeters. The digitals are smaller and easier to pack but the analog Spotmeter V's have their own special charm.
There are other quality meters out there but the Pentax is the benchmark for good reason. It's very easy to use and very reliable.