L.H.
Don't push or he will push back. I learned that the hard way (steam cleaning, furniture cleaning, mopping, laundry... you see where I am going...) He will go when he is ready. Let him pick out something of is favorite in the store, and tell him maybe when he goes on the potty like a big boy he will be able to have it. Then get the toy - on a SOLO trip to the store~(lets say he likes Cars from disney) and put it on the fridge (or somewhere out of reach, but nOT out of sight) and dont mention it until he sees it and asks for it. Let him know only big boys who use the potty can have it. Pretend it says that on the box if you want. He will get mad, but he will keep seeing the toy and be reminded. Then, make up a potty chart, and let him see the Cars stickers. Dont talk to him about it until he asks about it. Let him see you taping it to the wall and "organizing" the sticker sheets. Tell him he gets to put a sticker on the special chart for when he goes potty. When he puts a sticker in the days for a full week, give him the toy.
I definately reccommend letting him run around bare-assed so he can just sit on his potty at the drop of a hat. I have had to turn up the heat in the house because I am right now training my 2 year old daughter, but the extra cost will far outweigh the cost in diapers.
Dont push him, Dont force him, just give him very visable reasons why she should go. Maybe give your husband stikers when he goes, as he annouces loudly and HOPEFULLY takes in your son when he goes. Let our son see him getting the sticker. That works for some people. Good luck, like I said I am doing training as we speak, so I will be happy to keep you updated, and gladly take advice from you too.