Support your local bike shop vs. going to Walmart, if you have a local bike shop. You may be able to work out a trade in/swap when the kids outgrow these bikes, on their next bikes, if you work that angle.

Yes, you may pay more at a bike shop than at Walmart, but you will also be supporting your local economy vs. China's. (and yes, I know some small bike shops also sell cheap bikes made in China). But, you will also make a friend of the shop owner, who can then fix your kid's flats when you are out of town, if you can talk your wife into putting the bike in her car to bring it to the shop.

You might as well pick one up for yourself while you are there, and the wife, so all 4 of you can go on rides.