My instinct is definetely to buy as much as possible. My mother always gave us so many gifts as children and so did most of my friend's parents. I wonder if it varies by area of the country as well. We live in New England.
I wanted to respond to this as well, but was thinking about my answer. I don't think it depends on area; I think it has to do with mindset and how our childhood influences the decisions we make as adults.
My bio-dad makes a lot of bad decisions, has drug problems, etc. He bought his love so I got presents all the time as a child from him. Christmas and birthdays were especially full of gifts. My grandma was born into a large family and they had small Christmases; then she was a single mom to 4 kids and funds were limited so her kids had small Christmases. I'm not sure if my mom felt guilt for who my dad was or if she was trying to create a Christmas she never had or maybe both, but I generally had a lot of presents from her and my stepdad as well.
My DH's parents were very abusive, mostly physically. Christmas was their way of showing love b/c they rarely showed it any other time. DH & his parents reconciled when he was an adult and he understands better, though doesn't agree with, the choices they made for "disciplining" their children. It was not uncommon for DH to have a stack of toys/gifts that was taller than he was. With the children from his first marriage, Christmas was normally a pretty big deal.
Now we have DD, my only child. And I thought long and hard about how my dad treated me as a kid, how he tried to buy my love and how my mom tried to make up for her own Christmases. I wanted things to be different for my DD. And I think so far I've done a pretty good job. She gets plenty at Christmas, though not a huge amount from us. We do a stocking and 3 gifts b/c the baby Jesus got 3 gifts when He was born and we are celebrating His birthday. I know several families who follow the something to wear, something to read, something they want, something they need -- 4 gifts. There are other families that provides lots of Christmas presents, but it's full of things that are useful that will be used throughout the year and very very little is bought any other time of the year; only as things are truly needed.
I guess what I'm saying is think about the "why" behind what you want to do. What's your motivation? Are you trying to recreate your own childhood? Are you worried about what your family/friends would think if you gave your child a few presents instead a room's worth? Are you making up for not providing in another area? It's important, I think, to really figure out your motivation. I think you are right that what you do early on (those first 3 or 4 Christmases) sets a tone for the child's life. What happens in the future if you can no longer provide stacks of presents?