Thanks everyone for your suggestions.
Yes I live 15 minutes away from the border and do most of my purchases in US. I will check out the repellents at REI. I found their stuff a bit expensive though.
About border crossings:
I cross the border at least 25-30 times a year and have never had any trouble in the past ten years. As long as you declare everything you have, including liquor, cigarettes, weapons with a permit and the correct value of you purchases even if you are above your allowed limit, they will generally let you go. If you are carrying something questionable and declare it only if you are asked about it, you could end up in the dog pound. Border guards generally can 'smell' if you are trying to hide something.
Don't ever act smart even if they are wrong or rude. You may be able to declare your rights and win the battle, but not the war. You could get strip searched for the rest of your life at every border crossing from there onwards. Be polite and patient you could save yourself a lot of trouble.
They are very observant too. You think they won't notice something concealed in/on your bike or vehicle...think again. I once purchased a set of nerf bars for my SUV and it was lying on the floor of my vehicle. I had laid all other purchases on top of it and completely forgot about it at the border. I had declared everything but this. The border guard kept repeatedly asking 'anything else' and I knew instantly something was not right. I moved my stuff around and then realised I had missed the bars. He obviously had seen a tiny bit of the bars through the windows and waited till I declared it. I apologized for the omission and he was alright.
If you are driving at night, make sure your interior lights are on so that they could clearly see what/who is inside vehicle. Switch off your music so that you could hear them speak....respect!
Also if you are in a group waiting at the border, watch what you discuss among yourselves. Microphones have been installed close to the gates and they can hear what you speak while you wait. Dont be surprised if you suddenly get pulled over for a complete strip search
The crossings are packed with people during long weekends and that's when you often see guards walking between lines with dogs sniffing around your panniers and trunks. If you are carrying any drugs, that will probably be your last border crossing.
Good luck!