get yourself a 1W IR diode... you can probably find one for $50
If you want a gas laser, it's a bit more difficult. HeNe's only go up to a few mW's max (I think the strongest was close to 200mW). CO2 lasers are great, but I dont think they make anything as low as 1W. Usually a 10W will be the lowest power CO2 laser you'll find, and they are invisible. Argon will get you where you need to be, .5W-1W, but it wont really be cheap. Probably a minimum of $500 for an HGM5, which will do about a watt CW with factory cooling. With increased cooling they can do a bit more (some go over 4W), but will really need a ton of cooling. The HGM5 requires 240V single phase. From there you can get a water cooled lexel which will run on single phase and do a few watts. Anything much bigger than a lexel 88 will be 3-phase.