After a quick look at the specs I'd say $25 for that thing is a steal - if it works.
That thing has some funny features, like an auxiliary 12V, 50mA power supply output, comparator relay output or an input for a touch and hold probe. And it has a resolution down to 10uV DC and 10nA DC. Nice!
Edit: Specs say it has an internal battery. Second thing I would do is to check that battery (first thing would be to have a look at the power supply caps, just in case).