[chris vickery]

Many paint shops actually use a battery pack compressor unit which is attached via a waist belt and is a totally self contained system. It alleviates the need to drag hoses around and be tethered and eliminates the costs of a separate compressor system. I think they are over $1500... I suppose it comes down to how often you are using it, exposures, types of paints etc. More is better when it comes to protection but it also comes down to dollar and cents.
Re: Phil, if you can smell paint at all with a half mask it I not correctly fitted. This is a common mistake many people make is in purchasing the incorrect size and type of mask. It is also imperative to be clean shaven. At work, we must be fit tested to ensure the adequate size and type of respirator is issued and it is worn correctly.
Also, to get away from welding fumes there are a couple options. Low profile half mask which will fit under a welding helmet coupled with a smoke extraction system. Personally, I hate to be tied up with hoses when trying to move around with any kind of helmet/mask etc. Its OK for bench work but not much else.