next best price i could find was amazon £3.00, but found them today @ Home Bargain for 99p.
Set includes 3x meteor mud, 2x lunar lava and 3 moulds.
I know some people dont have one near to them and so the amazon deal may be better suited but thought it was worth a mention.
Worth a look if you have a local HB.
Heres amazon link so you can see a pic. sorry i dont know how to post pics.http://www.amazon.co.uk/Martian-Matter-Alien-Refill/dp/B001CZS22A