Hi, and welcome to the forum
As laserbee said a lot of your questions can be answered quite simply by reading a little, you'll pick up a lot! But I'll try my best to answer your questions.
Well, a green laser of any power 50mW+ will be able to able to be seen a long way away, so there isn't an issue there, and with a resonable power will also be able to burn and smoke things, but I doubt it'll cut through a credit card
You need around a watt or two of IR laser to do that
And you also mentioned your interested in a "blue" laser, now technically blue is 473nm (wavelength) and that is a true blue colour, how ever people often mistake this with the cheaper of the two, a violet laser which come from blu-ray players, these are actually 405nm and just on the border of the visible spectrum (390nm.)
Now true blue and green lasers work using a system called DPSS laser, this stands for diode pumped solid state laser. This means that a high powered IR diode is placed behind a set of crystals which basically transform the wavelength to 532nm (green.) This system also applys for true blue lasers. How ever the violet laser I mentioned earlyer runs on a basic diode system, these use the standard 5.6mm diodes you will find in your average DVD burner.
Buying the lasers:
Violet lasers are typically cheaper than the true blue laser pointers, true blue lasers within your price range are only around 1-2mW, which is very low powered and you would only buy one to use with a fog machine to get the full effect of the beam
How ever violet lasers are becoming much more high powered, the current diodes you can buy are:
PHR-803T@90mW
6X@180mW
8X@300-400mW
PHR's are very cheap, 6X a little more expensive (30$) and then 8X which are still experimental are around $150. How ever these lasers burn VERY well and are probabally the best to satisy your burning needs
If you did want to buy a blue laser, I reccomend laserglow as I believe they currently have a reduced price on blue laser pointers:
http://enthusiast.laserglow.com/GAP
For violet lasers I would recomend getting a respected member on the forum to put one together for you. Heres a few builders with very good reputation and customer satisfaction:
IgorT:
http://laserpointerforums.com/f64/fs-110mw-phr-140mw-4x-170mw-6x-blu-rays-22567.html
Very good builder
and Daguin who you could PM and talk to about getting a laser built.
Both are very good guys and respected on the forum, there are a few others which I've missed but those are two I can think of off the top of my head
Green lasers:
Green lasers are fairly common, if you are look for burning power and an awesom beam then there are several different choices.
www.0-like.com--Ê×Ò³
O-like is very respected company on this forum, often deliver overspec lasers and have good customer service, they are great for your cheaper high powered green pointers.
If you want to spend a bit more money then have a look at Optotronics or laserglow.
To answer your question why some lasers cost more than others, this is all to do with quality. You pay for what you get in lasers, the more you pay the better service you get, better duty cycles and more chance of getting an on spec or over spec laser.
Cheaper chinese pointer companys claiming "200mW" will often only be around 70mW and then refuse to refund you.
SAFETY
Very important matter, make sure you get safety goggles, your eyes are worth more than anything
I reccomend these for you:
Laser Glasses - UV to Green Lasers Protection 190-548nm :: Laser Safety :: Dragon Lasers
As they block violet,blue and green beams all in one which are the colours you are interested in, I own a pair of these and they are great
Please do excuse the long post, but everything you need to know is in there
Have a good day!
-Ash
