I bought two new travel cots for our grandchildren (both out daughters had a baby within a few months of each other). You can get them for about £35 - 40 from Toys R Us or Ikea. They're still going strong almost two years later.
Ikea high chairs are £15 so I bought those new as well.
Buggies were second hand from our local area Facebook buy and sell site. (£25)
Car seats - the biggest expense. After a lot of thought we spent about £130 for seats that will grow with the children to age 4. We could have bought them second hand for about £50 but I confess to feeling overly responsible, what would I do if anything went wrong, what if the 2nd hand ones don't fit current safety regs.
We were given all kinds of good quality toys, those baby walker things by other grandparents. As has already been said, grandchildren seem to be expensive - the little ones have so much 'kit' but they are gorgeous (and exhausting)