These are your babies. You must decide what to do with them. No one would admonish a wife for choosing how deal with the remains of her husband and the same should be true for a mother. You must choose what is right for your family.
We chose to cremate our sweet sons. I don't know why. But it seemed right. It didn't cost us any less since we still had to buy a casket and it got cremated too. The plot wasn't any smaller. I don't know why, but it felt right. My mother-in-law offered to let us use the plot next to her husband. She purchased a double plot when he died. And then we could bury her with the twins when the time came. But we visited the infant/child section of the Catholic cemetary and it felt right. There were beautiful trees and statues. It seemed appropriate that all the young children be together.
Others have chosen to build special shelves or cabinets at home for their babies. Other mothers have their baby's ashes in the nursery where they were always meant to sleep. Some parents have cremated their children and are waiting to bury them with themselves or another family member, or perhaps they are waiting to bury them after they move.
We still haven't ordered a headstone, but will be doing so in the near future. We have thought of having a prayer service done after the headstone is placed. What kind of services you have will depend on your family and religion. We are Catholic, but had a prayer service with immediate family, 8 people. We got childcare for our children so we could grieve privately.
Finances: It is almost worst to talk about money than death. But some morturaries, cemetaries or churches will do services for free for infant and pregnancy loss. Definitely ask about it. It can save a lot of money.