You need a power supply. This is an Argon Ion laser, it's not nearly as simple as hooking up a diode to an LM317 and calling it a day. Operating voltage is ~90-110VDC at ~8A (Up to 10A, only rated for 8A though).
You also need a lot of air going through the head (So you need a good fan, not just some computer fan you scavenged) ... these will dump about 1,000W of heat at full power, for a measly 0.015W of light output. Think: Space heater with a little pretty blue light and a big loud fan.
It may or may not work, you won't know until you find a compatible power supply to test. Could be an old tube, could have been sitting too long.
They are rated at 15mW 488nm - could do a little more in good condition.
I'd do some reading about Argon lasers (and gas lasers in general) on Sam's Laser FAQ before pursuing this.
Define fantastic ... maybe if it was known working and had a power supply. But fantastic is subjective, some people don't want a 30lb space heater that puts out less light than a $5 eBay pointer. Getting an unknown condition tube with no PSU can be frustrating and take a lot of time and effort to get anywhere.
This is coming from someone that has owned several of these (and others, see signature for example) - and I like them. But they aren't for everyone.
Yeah, that's pretty reasonable for a confirmed working set, assuming it's not end-of-life/high hours. Keep in mind shipping will be expensive depending on location. Think that's what I paid for mine ... +$100 shipping because I'm a long way from California...
If you are looking to get into gas lasers - the best way to start is a Helium Neon as there is much less to deal with and they usually run fine out of the box - just a tube and a power supply (small sealed box).
A bunch of us run these Argons and its a bit of a risk whether you get a working tube or not from ebay... and then you need the fan, power supply, and you have to cobble up a controller of some sort (simple as jumpering wires on the remote port or as complex as buying a digital controller depending on your funds, etc).
I love Argon, but don't recommend it as a first gas laser as they usually need some fiddling to get running.