If you are new to lasers read up on laser safety, maybe just buy a cheap eight dollar 532nm laser pointer from ebay. You should have safety glasses or goggles, even if they say under 5 mw on ebay, they don't tell the truth, usually 50+ mw.
Yeah, that or a 301 or 303 from eBay is plenty bright enough for astronomy. They are all around $8 and at night the beam is very visible. For an extra $2 you can even get a cheap 18650 battery with charger.