Many years ago when I purchased mine it was just over 300 bucks; best part is the ones these days that are around 60 bucks are much better now.
But you still do not get an air blast out of it; this is fine if your want to move something slowing or push out a dent in the bed of your truck; but sometimes you need to move it a little faster or really jolt it with an air blast.
I know what you mean with the over heating too, the older really expensive ones where great for this, the newer cheaper ones I played with in the hardware store did not over heat and the battery last much longer. CO2 air guns just last longer, they are lighter, take up less space and you can air slowly or blast it right out if you need to.
If your doing like I am and taking 20 or 30 CO2 cartridges into the bush, then the weight advantage is gone because you bring that in and out.
Buddy of mine had a small 3 inch HVAC stainless pipe closed off at about 24 inches long for a compression tank. His hose, tank and bike hand pump to refill came in lighter than what I carry, but he can really blast air out fast that way if needed. His sits right on the back of his Surly Bill Trailer out of the way from everything else, other than packing good and portable in any way he gets a long time out of it or lots of presure.
He once use two tubes a few times just south east of Cabbio. A storm had blown through pretty hard, lost of rain, lots of new wash outs, tons of wind. It was just a bad weekend. A couple weeks of good hot weather went by and I met up with him down there. We had a spot that we had been killing with the GPZ back when they where fairly new on the market, machines had already paid for them selves in that are with about 40 hours of swinging but we still where not done.
He gets to a few good size stones by a tree that has partially blown over, just enough to get a coil under the root flat. He gets about 18 grams total around these stones, then gets them out of there all together and finds another 11 grams, then like a smart ass I tell him to check that root flat. He said why not, works in the water, why wouldn’t it work on a mountain side. Uses his tube and mine to get that leaning tree more leaned over down the hill. He ended up getting that tree leaned over for about another 8 inches of clearance under that root flat after he pulled the tubes. More than enough space to clean out under that, he got another 7 grams under that root flat. Time he spent doing that was just under two hours, which is pretty darn good for Euro picking; the GPZ already makes it like cheating and worth actually doing in Europe, but that day was a great day for him and by the time sun down came I had 36 grams and he had 70 grams.
Yeah buddy

I was hoping no one was gonna bring that up! Crushed two with a claw hammer before the ole boy caught up with me....... These are $59 and are rechargeable. My only concern is whether you're gonna need 20 minutes and a whole battery pack to air up a bike tire. And whether the compressor part will have a tendency to get real hot like the 12v ones. I'll up date when my buddys comes.
Doesn't everyone carry a valve stem remover in their cars?

Works when you want to leave a message to the putz that parks 2" off your car door! Remove 3 valve stems and take em with you. Message sent!