I think you are misunderstanding the Express Card standard. The one I linked to above does fir, it only uses the left 34 pins of the slot. Most Express Cards are like this, the wider slot is for the extreley rare cases where 54 pins are used. I have various Express cards for my laptop that are 34 pin, fit the left set of 34 pins even though the slot width will take the wider card. click here
It's the way it works. It's a dual 34/54mm slot. I'm currently using this click here in my laptop. It's a 34mm ExpressCard and fits snuggly in the left hand part of the slot. I've never even seen a 54mm WiFi Expresscard. Either you accept the technology or you find another way.
I bought my Belkin Express Card for £7.90 delivered, so forget all the high prices you will see elsewhere click here