They make some really nice faux wicker baskets like
this one.
My LBS has something like that but in aluminum which is a lot nicer and much lighter.
If you can get your wife to ride then get her something nice rather than cheaping out. Something that looks stylish and classy with that fine English three speed that will make her feel good about riding it about and makes her feel chic and fashionable. Take a look at
Lovely Bicycle and see what a lady likes when it comes to fashion biking. That girl knows how to do it in style!