That's hands down the best advent calendar I have ever seen!
For our first Christmas together, DH and I could barely rub together the €12 for the cheapest tree we could find! I made felt decorations including pink martini glasses with olives 
Since then (2007) I have carried on making them but with more taste! I have also got on the tree some chandelier crystals (sold cheaply in boxes in flea markets). They also look nice hanging near a window to catch the light.
Decorations-wise I also have a wreath for the front door (we have a glass porch then another front door with a knocker, wreath won't get rained on, it makes me smile when I come home), mistletoe above the kitchen door, a knitivity (knitted nativity - we aren't religious but it is a wonderful thing to look at and full of character!), a 1ft snowman by the front door who holds a sign saying welcome - muted beigey colours but very cute, it was a gift. Also various hanging bits that I put on kitchen cabinet door handle, a Santa's washing line across the bookcase, various bits lit up with LED tealights.
Oh, and I make my fridge look like a snowman!
I have rather a large collection of little decorative stockings, I'd be more than willing to post you one 
but appreciate if you want to do it all yourself.
What I would recommend is getting yourself the nicest stocking you can afford, buy yourself little treats over the next few weeks and wrap them immediately (nail varnish, FC hankies, bath stuff, corkscrew, £10 note... etc), by the time Xmas day comes round and you unwrap your stocking-to-yourself, you may have forgotten what you bought! Surprise! Plus a tenner!
Biscuits and ribbon is an excellent way to decorate a tree, your biggest outlay being tree and lights. Then splash out in the sales.
