I'm spending less than $5 on each kid (prolly more like 2 or 3$ actually!), small fun candy valentines and very inexpensive gifts.
The older kids are each getting
one of these (SO many neat ideas there!) and the boys are getting a backscratcher that I got for one dollar. DSD is getting a little notebook with hearts on it.
DS 3yo is getting a puzzle and some sort of candy item, I haven't decided what yet.
Valentine's Day also happens to be my birthday so we are having cake of course, bday/Vday cake

I'm going to make heart shaped pancakes for breakfast that day. DS 3yo will probably color pictures to give to everybody.
I know Valentine's Day is so commericialized, but I've always liked it anyway. I've always told the kids that it's a special day to do special things for those we love and let them know how much we love them.