Hi BabyC, I was in your position last year, and about this time last year we bought a Quinny Buzz (with Dreami Carry Cot bit) second hand from one of my DH's collegues. We bought a Maxi Cosi Cabriofix car seat and an EazyBase new a few weeks before DS was born in September. I knwo most people love their Buzzes, but I hated mine!
I wouldn't recommend the Quinny Buzz, and certainly not a second hand one. It is very wide, and not very easy to manouevre. It is too bulky to be a nippy lightweight and too flimsy to be a proper off roader/jogger. It is neither one thing nor the other, is too wide for many doors, shop aisles etc and the front wheel just seems to be a direct descendant of the most twisty trolley wheels! But what really did it for me was that when ds was 5 months old, the big joint on the side which the car seat/Dreami/Buzz seat fits in just gave way and the seat swivelled back, dangling DS a few inches above the pavement. The third time this happened I decided that I wasn't using it again! It could just be that ours was quite old and that that joint was knackered, but I went right off any prams/pushchairs of this desigh like the Buzz/Chameleon/iCandy Apple.
A few other gripes about the Buzz - the shopping basket is tiny. I know 5 people with one, and the hydraulics have gone on all of them at some point. And the Dreami is quite small - DS was too tall for it by 4 months, and he is not that tall.
Although I did like the Dreami when he was tiny - he could lie flat and be protected from the winter weather around him. I know the Buzz seat lies flat too, but he was an autumn baby and I am not sure that the Buzz woudl have provided the weather protection that the Dreami did.
I now have a Phil and Ted's sport. It is light, sturdy, MaxiCosi compatible, and has a great shopping basket! It is also 2" narrower than the Buzz - so it gets round corners, shops etc easily and passed wheelie bins on pavements - and the front wheel in on proper bearings - so it doesn't get cocked up on itself. And it is so easy to manouevre. It is chunky when folded though - I wouldn't want to take it on public transport, but since we hardly have any round here, then that it is not an issue for me. It's big wheels take our local footpaths and bridleways in it's stride though, and that it what counts for me!