I have had very good success with Winsor & Newton. As one of the earlier replies states, one tube will last for years. In contradiction to one of the first replies though, I have had very limited success with Tamiya paints; therfore, I won't make a comparison with them. You will still want to use a base coat of either an enamel or an acrylic paint. I use mostly Humbrol for this but have used Model Master Acryl with good results. Remember to let your base coat dry at least 24 hours before applying the oils. Good luck and have fun experimenting.
Bull
p.s. I would recommend finding a copy of Verlinden's book on figure painting as he does an excellent job of writing out a process to follow for using oils.