One of the local bands solves the portability problem by having all their sound setup on a single cart so that it can all be rolled in with most of the hookup intact. Once you've got wheels under it, the weight is less of a problem, although it never goes away completely.

In the cases where I've seen the setup, they used "house speakers" that had a convenient plug-in point, and I would presume they had their own, carried separately, for when they were needed, but the speakers aren't usually the heavier lumps that need to be handled.

The cart they were using probably came from a music equipment supplier, but very much resembled a "service cart" of the kind found at restaurant equipment places, and the restaurant carts generally appeared to be sturdier, and had bigger wheels (a real advantage in gravel parking lots?) - and might be cheaper. "Restaurant stuff" also is usually heavily protected against corrosion so durability almost always is excellent.

A discussion with the sound guy (who happens to also be the banjoist) indicated that there was still a bit of difficulty lifting the cart in/out of their vehicle (a 2-person job), but I inferred that the physical size was the problem, rather than weight. I suggested looking at the ramps/lifts offered for transporting handicapped aids/equipment like wheelchairs or scooters; but I haven't seen him since to know whether he did take a look. Most semi-medical stuff is exhorbitantly overpriced, but once you know how they did it you can usually find a cheaper way to get it done.

Of course the sound/electrical stuff is probably best obtained from proper sources, but I'm an advocate for "unintended uses" of things that work better for my task than for the stuff it was "intended for" - as long as it does my job better. (Better almost always includes cheaper, but sometimes you can only get what you can pay for.)

John