Winter Cycling - Water Proof Spray for Winter Cycling Gear?

My grandma found a goose down jacket at goodwill, and gave it to me. It's fairly light weight, but very, very warm. Can this jacket be sprayed with a waterproofing spray to create a cheap winter cycling jacket?
I know that these jackets aren't very breathable, and I may sweat, but I will have a wicking base layer.
What are your thoughts on this? I'm trying to do this winter thing on an extremely tight budget.

Thanks for any help guys.

Nice jacket... but you are gonna bake like a Christmas goose in that.

Nice jacket... but you are gonna bake like a Christmas goose in that.

That's what I'm worried about. Maybe a base layer, a used wool sweater, and a used spring jacket sprayed with water proofing. I normally don't spend a lot of time in the cold, I tend to hide in the winter. I've been riding with a base layer, thin sweater, and a sleeveless jacket which seems to work fine, but it hasn't really been cold yet either.

Nikwax Downproof will add some water repellent treatment to the down. It is a wash-in, not a spray on so everything gets treated.
Down is only useful when it gets seriously cold, below -10C or worse, otherwise it is just too warm.

Nikwax Downproof will add some water repellent treatment to the down. It is a wash-in, not a spray on so everything gets treated.
Down is only useful when it gets seriously cold, below -10C or worse, otherwise it is just too warm.

Looks like I'll go to goodwill and find a lighter jacket, and running pants, water proof those, and then water proof the down jacket the way you recommend for any extremely cold days. Thanks for the suggestions guys.

i just like windbreaker materials in the cold. works much better than waterproofing or waterproof stuff below freezing IMO for all outdoor winter activities.

I wouldn't worry about waterproofing the running pants if you'll be riding when its frozen out.

sloppy, wet snow is one thing, typical frozen conditions and snow usually can be handled with windbreakers or a softshell jacket.

Look for a product called Campdry http://www.kiwishoeshine.com/KIWI-Camp-Dry-Silicone-Water-Spray_p_454.html. Be Warned, once a down jacket gets soaking wet, it has zero thermal protection properties.
If anyone is handy with a sewing machine in your family, put some zippered vents in the armpits.
Vents only need to be 4 to 5 inches long. Your local cleaners may be able to do it for you also.
If you can't picture what I am talking about, go to a major sporting goods outfitter and look at some of the extreme outdoor apparrel.