These kids' wheelbarrows aren't cheap (although prices do include carriage) but they do look to be of good quality: http://www.mower-magic.co.uk/acatalog/Just_Like_Dad.html
(Since this site is primarily for 'grown-up' gardening items, it suggests that you might find something similar in shops which sell the full-size items - or in garden centres. Buying online is always going to mean that you'll be paying quite a bit for carriage).