Is there a hedge trimmer that looks like a chain saw?

I imagine you mean a petrol hedge trimmer. Most professional gardeners use these. However they are relatively heavy compared to electric trimmers. So you need strong arms to keep going. If you are thinking of buying a hedge trimmer consider a Stihl. Not cheap but the best electric on the market.

Why go to all the bother and danger of lugging a cable around a garden?

Always go petrol unless your garden is so small it doesn't justify one.

How about getting a neighbourhood co-operative to get a pool of decent quality tools?

Like this:

http://www.homedepot.com/p/BLACK-DECKER-22-in-Cord...

?

That's what everyone I know uses.