What happen to my sweet little boy???

Lately Kaden has not been the sweet boy that he has always been. He doesn't want to pick up his toys, get dressed, say his prayers, etc. Not that he always came running when I asked him to do something, but he did what you asked and generally wanted to please you. All of the sudden EVERYTHING is a battle @ home (thankfully he is still VERY good @ school). We are just really struggling with what to do with him. I want him to be a good listener and be respectful of us and his things. A perfect example of this was that we were at Barnes and Noble Book Store the other day and they had lots of toys clearenced out. I was digging through them and I found some playmobil construction sets (which was a super find b/c playmobil is super expensive and rarely goes on sale). These were perfect for him b/c he received the playmobil construction crane from my parents for his birthday and the construction garage that goes with it for Christmas. I was not about to just buy it for him since he had just gotten a bunch of toys for Christmas. So, I asked him if he would like me to buy it and he can do special chores and projects around the house to earn the set. What was his response?? "No thanks, I don't want to earn it" Are you kidding me??? My son, who LOVES anything playmobil just turned down getting a new set b/c he "doesn't want to earn it"!!! Then the other night Kaden didn't want to get his pajama's on b/4 he went to bed. So we said okay you will just sleep in your clothes then. This battle went on and on and on and on! That is how the below "toy jail" got started. The cabinet is so full now that the doors won't even close on it. Hopefully this is just a phase and he won't continue to act like this but if he does I will be ready b/c I am starting a parenting class (love and logic) @ the end of the month.