You'll find the best Insights at Honda dealers, but prices remain strong - especially around London where the model is exempt from the congestion charge. You're unlikely to grab a bargain, but it's worth aiming for an ES model as it comes with better standard kit including cruise control, a leather steering wheel and gear lever plus a USB port.
The Insight will be available in larger numbers than the Civic Hybrid, but it will still be a fairly niche car for many. Lots of buyers aren't aware of what a hybrid is - or the benefits it offers. Use the impressive economy and cheap road tax as key selling points.