Got a 2nd hand baby jogger citi mini for $180 In 2010. Bought it because it was light, from birth up, and we lived up 3 flights of stairs at the time DS was born, so light-and-easy-to-fold-and-carry was vital. We still using it now to cart a VERY tall 36lb DS, who's 2, about the place (mainly cos I can't physically drag him away from the swings, etc, he's too heavy to carry when protesting. But I CAN buckle him in. Mean mean mummy..)
You can use it from birth, we LOVE the one-hand-fold (that's what sold it to DH!) and I've taken it twice on transatlantic flights.
Think about your lifestyle. What're the pavements like where you live? (bad pavements/ lots of rough tracks and you may want air tyres). Do you want to jog with the baby in the pushchair? Will you / dw be mainly walking around your home area and on public transport (light, easy to fold with one hand) or using it out -of- the-car (weight less important).
For us, it really mattered to have a single handle (because I'm often walking the dog at the same time, therefore only have one hand for the pushchair, and also to have a decent hood as we live somewhere that can get v. hot and sunny.
That put me off the Maclaren XLR, which was our other best lightweight, from-birth 'other option' - it's a 2 handled pushchair. But otherwise well worth your consideration :)
Now looking at 2 seaters - but the Citi Mini has seen out 2 kids over 5 years and doesn't have even a rattle, it's a bloody good buggy. You can also clip a carseat into it for a few months, which if you have a sleeping baby in the car and just want to clip the carseat on, is a GOOD thing!
Every single mother I know who bought an expensive travel system got rid of it within the first 6 months and got a MacClaren or City-Mini/Quinny style thingy. EVERYONE. Even if you can't persuade your DW to go second hand, I'm fairly sure you can talk her down from the nearly-a-grand models to the 200-300 quid new models. You really do need to find the one you like and think will work, it's like a car, you'll use it multiple times a day.
Oh! And get a sling. Ergo worked v. well for us, used it for nearly 2 years. DS was happiest in there for the first 6 month of his life, wayyy happier than anywhere else. And we could get other stuff done so easily! :) Good luck!