Anitas glue for crystals, gems etc
Double sided tape from Wilkinsons- sticks vellum fine and costs under a quid (it has no backing paper either side either, so eay to use)
Lots of papers: The Range and other places do a5 sized books with loads of pieces in for £4 ONO. They're great whilst you are aquiring a stash.
A fiskars card boss is great- Chrsitmas? Once you get one, you can do a card for nothing but the cost of the blank.
An Ebay account (!!!)- great shaker boxes on there at the mo, bought some lovely lilac ones
Individual alphabet stamps are handy, I am after those for christmas myself!
Watercolour pencils, gel pens and / or chalk palettes
Oh and emergency stickers for the little marks you want to cover!!!!
For good papers / vellums (I love their glittery vellum), I use www.ctaftsulove.co.uk and for funkier papers, www.modernscrapbooking.co.uk
Oh. Storage, V V Imporatnt. I have one of those large plastic drawers- on wheels type units, works a treat