Seeing the air dry clay there has reminded me to remind everyone to check out if they have a scrap store near them if they want any sort of arts and crafts bargains...
scrap store directory
They are brilliant - because they collect stuff from local businesses that would otherwise be thrown away and then resell it at bargain prices.
My local one in MK has a craft shop attached which sells new supplies (often much cheaper than in art shops - I got a large pack of air dry clay in several different colours for a couple of pounds or a kilo brick of plain stuff that could be painted for about a fiver, packs of 5 big A4 notebooks for a pound, packets of 100 sheets of coloured card for less than a fiver etc) and then you have to be a member to access the scrap - which in my local one includes things like left over rolls of paper from the end of print runs, about 80 cm wide and about 100 metres of paper for £2, 8 wooden discs for a pound (the holes they cut out of Marshall amps apparently 
, 20 sheets of A0 silver or gold card for a pound, 9 big bobbins that held wool or yarn (and great for turning into Christmas trees with the dc) for a pound and so on. Plus you get 10% off in the main shop. There's different stuff every time you go - I've bought a new keyboard for £3, there's often stuff from shop displays that have been taken down and not needed again, there's loads of fabric (I got about 7 metres length of felt, full width, for less than the price of 3 pieces in John Lewis or Hobbycraft) and so many bits and bobs...
It's also a charity that runs free play sessions for kids and training sessions for adults working with kids, and it's a win win for everyone - the companies don't have to pay landfill charges, landfill isn't getting filled, people are making good use of stuff for dirt cheap prices. My dc love the place - and I think I'm going to give them a christmas fiver each to spend there as they will have hours of fun choosing stuff, then have many hours more fun making things with the stuff they've bought - might have to do it at the start of the holidays though to keep them quiet and get some decorations out of it while I'm wrapping their presents!
Sorry, just realised that's a bit of a long post. But really really worth looking into if you have one near you and you/your dc enjoy crafty things!