I'll agree with everyone else - wait until you've had the bubs to buy. If you REALLY need one right after the birth eg bubs won't feed off you then the hospital will provide you one anyway so you'll still have time to purchase. I'm glad I waited as I was thinking of buying the Medela Swing (single) but I now pretty much express all my bubs feeds and have really needed a double. I purchased the Medela Pump in Style - pretty much hospital grade - and use it 7-8 times daily. I've also got the 'hands free' attachment from the USA for it and have learned to express while bottle feeding the baby
So just wait to see how much expressing you'll be doing before purchasing. Here's a handy chart
Choosing a Breastpump