Creative Art Materials"Caran D'Ache NeoColor II" Water Soluble Wax Pastel Set, Multi-Colour, Pack of 30 This set contains a very good range of colurs and will last for a long time.You could take a small selection of favoutites for travelling.
Pentel Arts Aquash Water Brush Assorted Tips, Pack of 3 (FRHBFMBP3) The best way I know of carrying a supply of water and brushes when on the move.