Do yourself and your kid a favour and get a baby sling first. The cosy fabric wrap kind. Then when you've got the hang of it and know the kinds of things you do with your kid you'll have a better idea of what you actually want from a pushchair.
Then get a Quinny Buzz. The baby can face you which is important at first, and it's inexpensive, folds up small and works well.
I'd avoid a travel system as they're crappy plasticky monstrosities and when you get a sleeping baby out of a car seat and put them in a sling they just snuggle up to you and go back to sleep anyway.
Also the carry cot things that fit to a pushchair frame to make a pram are useless if you have hills because the baby slides down one end or other in a heap.
My fave sling is from Close Parent.
By the time they are getting too heavy to carry, your choice of buggies opens up and should be considerably cheaper
Yep. Once they are old enough not to need to be facing you, you can get a Quinny Zapp which is only about £120 which sits on the wallet a lot better than a £600 buga-bloody-boo.
Best advice I have is to go minimal. Parents are encouraged to buy tons and tons of junk and then a big car to cart it all around - almost all of it is not necesary. Just get the absolute minimum and then get more if you really feel you need it. Most people over-shop at first then leave the stuff gathering dust in the garage.
Oh and pushchairs take a beating so second hand ones are often trashed.
Although.. Chariot bike trailers are also the best pushchair I've ever used...