First of all, congratulations! A first grandchild - you must be so excited!
My DH restored and renovated the old cot my DC used and that is up in the spare bedroom, complete with a new mattress and bedding. We also bought a used moses basket for when she was tiny (I bought a new mattress). We had a bouncy cradle - so very useful, we couldn't have done without that. I bought it secondhand and washed the covers. When she grew out of it I sold it for the same price I'd paid for it!
We also bought a lightweight buggy so that if DD and DGD are coming out with us in the car (she doesn't drive), then we can more easily stow it in the car than her big pram. And rather than buying a highchair - even a fold-up one - we bought a little seat complete with tray and harness that straps onto one of our dining chairs. It folds away when not in use and is so handy to take with us if visiting people.
And then the bits and pieces: bottle, bibs, coveralls, bowls, spoons, nappies, muslin squares, wet wipes, nappy bags. Yes, DD usually brings everything she needs when she visits, but it's worth having them as a backup.
You will have so much fun shopping for the little one - I know we do 