If you do not have a Deere dealer near you, you can try ordering them through a Lowes home improvement store, if you have one of them near you. Of course.... i'm talking about the weights that are about forty pounds. I believe Lowes will ship them to your local store and you can pick them up there..... saving you on shipping costs.
Do these look like the weights you are looking for?
I found two at a locals guys place that specializes in used lawn & garden, and compact tractors...... saving me a few bucks.