Stuart was asking about this topic and the following additional notes may be of interest.
I found a cheaper place than the one in the start of this thread so you may want to try them.
http://stores.ebay.com/QualityFoto_...1QQftidZ2QQtZkm
I bought the following filters (all for cokin p series)
graduated tobacco
graduated neutral density
circular polarising
mike also bought a graduated sunset
If I were buying again I would also get a couple of neutral density filters in different strengths (QualityFoto lists ND2 and ND4) and a couple of the stackable P series hoods (they have 3 for $14.95) and possibly a cross star filter and a graduated sky filter.
If you have the standard Canon 17-55 lens you will need a 58 mm T adapter which QualityFoto doesn't have listed, but most likeley will have; email him and ask, you may want to also buy T rings to suit any other lenses you have.
Make sure you read the notes on shipping as they all seem to charge per item unfortunately and there are some notes on combined orders as the first item is $4.25 and each additional item $2.00. The note says
Combined shipping - If bidding on multiple items, please complete checkout after all auctions have ended to ensure you receive all S/H discounts. Once you complete checkout, you will not be able to combine additional auctions.