
I have a Doghealth trolley
http://www.doghealth.co.uk/products/dog-show-silver-cage-trolleyThe whole undercarriage (wheel axles and handle) come off and can be re-attached in a couple of minutes, even by me :-). It is very lightweight, very durable and at £50 is unbeatable value.
It fits into the car easily, is lightweight and the only problem is me--I load it with 2 dogs, a couple of crates, and various paraphernalia and suddenly I'm pulling about 70kg behind me. It doesn't sound like much, but if the reason we have a trolley is to spare your back it doesn't help to half twist your spine while lugging your dogs and kit a quarter mile through tufty car parks, mud puddles, etc :)