It doesn't have to be expensive to be good!
I just ordered my fourth YES bra off ebay and someone sent to me from HK. I've purchased about 5 different brands of nursing bras, and the YES bra is the least expensive and the one that gets worn the most. It's the only one comfy enough to wear to bed. And the black one is rather attractive. I think it's funny that I found the YES bra when I was living in the States and now I've moved to where they're manufactured.
Graham, you said that your wife would like to breastfeed. Has she gotten any support or gone to any Le Leche League meetings? Maybe she feels like she won't be successful and doesn't want to invest in a nursing bra? I remember being so stressed out and wanting to breastfeed so badly, but I encountered a lot of problems in the beginning. It was only because of the support and encouragement of my husband and the local Le Leche League leaders that I was eventually successful. I couldn't have done it on my own, and you're a very good husband for taking such an interest!