I'm pretty certain it was this guy
http://stores.ebay.co.uk/The-Syringe-Shop
but there's none there at the moment - maybe you could try asking the seller direct. A pot was about £12 but will last you ages - you use about 4g to make up 100ml of agar. Alternatively you could use DME and gelatine.
http://www.unm.edu/~draper/beer/slantuse.html
Re-using Yeast, is it worth it?