With 2 kids, I've got through
M&P Pliko - all but trashed by DS1, but serviceable enough for DS2 until he could sit up better. Bought full price, since for first baby!
Graco Citisport - really light, easy to fold and great for in the car, but too flimsy to feel safe on bumpy pavements - always scared the wheels would fall off. DS2 outgrew it, this Spring, though. Bought half price!
Big M&P 3 wheeler jobby. Rather ungainly, but actually stood up to DS1. Have only used it in bad snow with DS2, since it's horrid on kerbs and to get through doors and consequently, it stinks from being stored in a damp garage. Bought half price
Some Zooper jobby. Bargain off ebay, tough as old boots, but ran it into the ground carting DS2 around the village for 2 years and he outgrew it, anyhow.
Quinny Zapp - given to us by a friend for taking in the car when DS2 outgrew the little Graco. He's now pretty much outgrown that, though!
Maclaren Major - because I walk 3-5 miles a day on school days and DS2 can only manage a fraction of that, since he, too, is hypermobile and gets tired very quickly. Bought off ebay, complete with all the rain gear, which is expensive to buy.
It seems a lot, but now, it doesn't seem so bad, after all!