This question gets asked a lot.
For just pointing around at stars, 5mW is ok. I like 50mW on a dry, clear night (beam is slightly less visible without humidity. Less than 50mW is usually perfect.
For mounting to a telescope as a guide, 100-200mW is great. It's just visible enough to be seen clearly through a telescope so finding objects is easy.
If you want a high quality 5mW:
The Wicked Lasers Core gets good reviews.
I prefer to shop at Z-bolt.com and Laserglow.com
https://www.laserglow.com/int-handheld.htm#
Premium Green Laser Pointer - Emerald Series
If you want something cheap, I recommend this:
True Green Laser Pen 5mW - Free Shipping - DealExtreme
This one is not as good quality and usually are between 5-30mW, sometimes more.
Other stores like Lazerer, Cajunlasers, O-like, have similar lasers but will probably cost more than DX.
Lasers more powerful than 5mW have import restrictions but hardly anyone has their stuff confiscated. It does happen, though.
If you don't mind spending closer to the upper limit of your budget, I would get this:
X50 Compact Portable >50mW Laser - X-Series - Novalasers Inc.
I've ordered several times from Nova and I haven't been disappointed. Also, they have friendly staff and you can ask them specifically for one with low divergence, stable power output, etc. and they will do their best to meet your needs.
It's been a while so hopefully that hasn't changed.