Toddler - 3T Winter Clothing

I'm looking for suggestions on where to pick up some winter outerwear for my 2 1/2 year old son. As we all know they grow out of their clothing in about 3-6 months so I do not want to spend very much.

I'm specifically looking for;

winter coat
leggings for snow play
hats/mittens
sweaters
boots

I'm open to good quality second hand shops or if anyone knows of any upcoming fall sales, please share. :)

Thank you!!