I feel excited going to Beijing on December 23 to 28. Can I buy shoes for the winter there?

Yes, you can buy the shoes for the winter in BJ.
For the gadget, do you mean the shoes? if so, it is hard to tell, because the price varies according to different quality and quantities. Usually, it is around 1000 to 2000RMB for a pair of shoes.

hi. I just return from BJ.are u taking a tour guide there? if so u need to shop for all ur clothes n winter shoes earlier before u go to BJ, bcoz in my experience, tour guide there wont let u stop for any shopping centre until the last day of ur holidays.i had to sneak after our lunch n buy the winter boots for my son secretly from the street hawker(actually we were advised by our tour guide not to buy anything from them-fearing they might return u fake money).If u r going by urselves and plan to get ur own transport- it is very hard to get taxis-especially if u r not a local .Many of taxi drivers couldn't speak english.The hotel receptionist also cannot speak english.we were considered lucky coz there was a chinese guy who sincerely help us to get taxis from the hotel on our night out another young chinese girl who help us to return to our hotel by helping us 2 get the trishaw(after all taxis hundreds of them refuse to stop for us)-so if u want to buy ur winter shoes or boots try to get it earlier before u go there.