you may know that to our eyes 7W does not 'look' much brighter than 5W.. to 'appear' twice as bright a you need 4X mW not just 2X-
so you need 20mW to see double 5W
and for twice as bright over 7 W takes 28W.
For your needs I suggest getting a JETLASERS lasers PL-E Pro 450 blue-- extremely well made- a for-real warranty,
and the duty cycle is fairly long-- big laser = long duty= big heat sink.
another good choice may found at Sanwu.
I go by the touch method on knowing when to rest.
I never run any of my JLs to the point that it feels very warm on the outside. as that means it is VERY WARM/HOT inside.
IF you do not,at this time, own best quality eye protection--FIRST--never after.. you can have JL include a pair when you buy.
also being so VERY dangerous you MUST keep the laser AWAY from adults w/ no knowledge and all youngsters.. without exception!!
store w/ batteries elsewhere. if you choose key lock --remove it when in storage..
it can pop a ballon in 1/2 second.. smokes wood almost instantly.. so any eye exposure could be VERY HAZARDOUS.
SAFETY IS AND WILL ALWAYS BR NUMBER ONE HERE!!
IF THIS IS YOUR FIRST ever laser-that may not be the best idea-
like if you have only owned a bycicle would you move up to a 140mph Ninja Crotch Rocket ?>
I am NOT trying to 'rain on your parade'
I don't think anybody would be willing to sell an already built handheld unit for that cheap (if you're looking for an engraver, you should look into CO2 lasers as they are quite a bit cheaper), but you might be able to build one yourself for <$200 (not including batteries, charger, or shipping) using parts from an eBay seller who happens to also be part of LPF:Like 200$ at best, thats why im looking for a used one