- Offer a tablet to your wife
- Buy reusable diapers (it's more trouble, but cheaper on long run)
- Explain to the wife about the dangers of some plastics (BPAs, phtalates) and convince her to buy form local artisans (without trying to be political, tell her some of the toys are made by kids not much younger than your own)
- Put stuff in boxes you know she won't use. Store them away from her (a shed, storage unit, etc). After a year or so, ask her if she knows where item A,B,C is, and if she needs it. More likely she will have no idea where it is. Explain to her that if the last year she didn't needed that purple striped sweater, she probably won't need it ever. Suggest selling or donating.
- Ask for hand-me-downs from friends and family for your kid. It will be harder for he to justify buying new clothes ('But he needs a new pair of trousers') when you can point to the bunch that was given to you.
I think just those 5 things reduced a lot of the stuff we have in the house.
You will have to manage this of course, you can't expect everything to go your way. She will buy that dress/shoes, but avoid you doing it too just because she tells you also need new shoes. Also, we go on vacation (for her benefit as I really not into it) every once in a while. It is a partnership after.