trailer bikes - know anythng about them?

[basketcase]

DH and I are really trying hard to get fit before we are too old and it is too late
We cycle regularly, daily through summer, and have two child seats for the DDs. DD1 is 4 and getting too big. We recently hired a trailerbike on holiday and she loved it, would like to buy our own. Found plenty on ebay and cycling websites but need some advice about which one to go for..
Has anyone used these? Are they worth the money (£90-400) and how much do you need to spend? Can you get away with a cheaper model or are the more expensive ones worth the outlay? We tend to do about 10-15 miles a time through fairly ok rural lanes - we have hybrid bikes.
Hope someone can advise us
Thanks xx

bump
sorry - I know this is a dull topic to many but if anyone out there knows anything, will be really grateful.

Also, do they come apart easily? we use a roof rack for the bikes, and need room for two kayaks and two bikes so hoping that it will fold away in a boot with little trouble?

My friend bought one off eBay but tbh, I haven't seen her use it very often. I think it's a bit awkward in suburbia coz you're not allowed to ride on pavements...... and it feels too risky to ride on the roads with the extra width the trailer adds. So many nutter drivers out there . But if you're riding in rural lanes, this might be better. I'd still be scared of cars racing round corners though (but got knocked off my bike by a speeding driver when I was a teenager, so maybe this is just me). Not sure about the quality - I'd go for middle of the range & probably avoid the cheapest ones. The ones they have at Centreparcs were always good...

thanks ionaming
I don?t think the bikes add any extra width as they are not the little tent trailer things, just an extra half bike attachment which adds length rather than width? If that makes sense? I am scared of fast drivers round country lanes and that is one of the reasons why I like the idea of her being attached to DH?s bike rather than on her own one - also so we can go further without her getting puffed out after 200 yards..

We've got one of these which attaches to DH's and DS1's bike and lifts the front wheel of DS1's off the ground. The bracket stays on the front of DSs bike so you can easily attach and detach it. And it's nice and easy to store - lives in the boot of my car at the moment - it's a telescopic pole about 1.5ft long.

thanks soupdragon. Will show this one to my DH as it looks like a sensible option