I agree that whether or not you ever have baby #3 you don't need to store things up. A few clothes or mementos, sure, but not everything.
I held onto stuff for way too long because my first two were born back to back and I couldn't bear to think that my childbearing years were over. But then we had a huge gap during which time I held onto everything... and then spent money and headaches moving house several times with all the stuff in tow. Just not sensible. We did get rid of most things before this last move, and it was wonderful to let the stuff go.
I kept my favorite carriers both for sentimental value and because they can be used again. Kept a few clothes in both genders - and I know we're only going to have this last kiddo so at least half of the stuff will have to be gotten rid of (if it's even the right season/size to fit this one!). And I kept a small box of treasured toys and books that are good as hand-me-downs. That's really about it.
We are expecting baby #3 around New Year's, actually, and this is what I ended up buying:
- car seats - $200
- a new cloth diaper set - $400
- a few baby clothes from the thrift store - $50 - and that includes outfits in bigger sizes as well
- a baby bouncey thing from the thrift store - $5
Umm, I'm trying hard to think here. I think that's about it so far... I'm going to get a new labor ball as I lost the plug thing to my old one. My mom is going to send up a crib she bought for DS#1 that's still at her house. It's never once been used - we co-slept until he got older. But she's moving anyway and it was an expensive crib AND it matches our new bedroom set... so she'll send it up. Otherwise I'd get a bassinet and then a Montessori style infant mattress when he/she gets older. And we might get a pack-n-play although I'm not sure - and I think we'll get it used anyway. We don't have a stroller and aren't getting one until baby is older.
So while that's our situation and obviously YMMV... the lesson here is that baby stuff is pretty easy to come by and there's no reason to store stuff beyond the immediate child.