Short answer, you got scammed. **Danger** And it's probably spewing tons of IR that you can't see, but can still damage your eyesight. Search the "Green Laser" and "Safety" boards for threads about "IR" OR "Ebayser"
First off, pyro is right - you were scammed. The laser you bought it putting out 20mW if you're lucky. Its a common scam on eBay.
Are lasers dangerous? Of course. Think of it this way: If a laser beam can pop a balloon on its own, what do you think is gunna happen when it gets focused through the lens of your eye? Retinas don't like being burned...
Burning laser for a reasonable price? Well, what are you looking to burn and what's a reasonable price? You can get a decent novalaser that will burn in the $100-200 range. You can get even better burning lasers in the $300+ range, some of which I myself could offer you . Unfortunately lasers are expensive though, and if you want a quality laser for burning, its gunna cost you. Sorry for all the bad news!!
Chances are, you paid for 240mW, and you got more like 20-50mW of green with ~200mW of IR. IR isn't focused by the lens the same as the green (it's also not coming from the same distance from the lens) so it usually diverges much more than the green and is only really dangerous up close (maybe within only 10 Meters or so...but who knows?) But the real worry is because you can't see it, and the 532nm blocking goggles I'm sure you've already purchased DON'T block IR.
So the danger, as with any laser, is getting anything but VERY diffuse light, be it IR, red, orange, yellow, green, blue, indigo, violet, UV, whatever wavelength, into your eye/eyes.