For me, teaching my son responsibility doesn't go into monetary issues or money. I myself feel that this is too much for a youngster to have to concern themselves with, mainly because A. it is abstract and B. they don't have the math skills to support this. I also feel that I don't really have to bring up the subject when my son asks for something. I don't make it about the money, I make it about using our good discretion.
For example, the other day we went to the toy store for some new tub toys we'd discussed getting. (The old ones were pretty gross.) While there, my son asked for a toy that he wanted. I first empathized with this desire for the toy, and then explained "Well, sweetie, our plan was to come here for tub toys, and you have picked some out. Should we remember that this is something else you really like and we'll have an idea for another time?"
Money is only usually mentioned when he's being rough with an object and we explain that if he's not safe/careful with that object (say, daddy's shoe) we will have to spend money to replace it and then there might not be money for toys or other fun treats.
Responsibility in our house comes in fulfilling daily expectations. I expect him to dress himself for school and bedtime. I expect that he will clear his plate and meals, help put away the toys that are out, take care of his toys and tools outside. Responsibility means staying close and playing in the yard when I have garden work to do so that I can do it instead of chasing him down the street. Responsibility is making it to the potty on time (care for one's self), getting dishes for himself when I request them, wiping up messes and spills with rags and throwing all his laundry downstairs for the washing.
I love the idea of teaching nurturing. We're planting peas and carrots this year, as well as some edamame and zinnias. We are excited to make our world beautiful and to grow food. Responsibility is also finding a worm and putting it in the composter, or taking care to not step on the ants, but to watch them. Pulling weeds or digging out a bucket of dirt from our big garden patch for me to put somewhere else-- he's a great helper.
As far as taking care of things, sometimes I remind him: "Well, if you leave x out, such and such might happen to it, and if you choose not to take care of your toy and it breaks, we won't be buying a new one." This is enough for him to hear. If toys aren't put away (big upset on his end, uncooperative) I just tell him 'Well, I see you aren't ready to take care of these toys, so I'm going to put them away for 7 days. We'll see if you are ready to take care of them then." and take them down to the basement. Sometimes, children have too many toys in their room and maintaining this is overwhelming to them. I try to rotate stuff out when I can see it's too much for him. It's all about balancing his 'stuff' and trying to keep balance in our relationship, so I'm not on his case about picking up AND the task of picking up feels do-able for him.
Responsibility is involved in much of what we do, whether it's staying together at the store or being a helper by helping to unload groceries. I think teaching care and maintenance of everyday items--both by example and practice-- is very informative. We ourselves don't have our son 'earn' toys, per se, but sometimes he'll receive a toy to celebrate overcoming a personal challenge. Like blowing his nose-- to celebrate his learning/mastering how to blow his nose, we took a special trip to the toy store and bought that toy he wanted on the previous trip. I myself would like his focus to be on his personal growth and not always 'what's in it for him'. I think focusing on money in this way would likely subvert that for us. All of this that we do is just presented as being part of/caring for our family. Sorry this is so long, and it's a very interesting subject.