Below we've included Winsor & Newton WINTON & Daler Rowney GEORGIAN both being good quality studio oil paints at a great price point.
Most colours are a direct alternative name wise with the exception of Midnight Black, Mountain Mix and Dark Sienna for which we suggest Lamp Black, Paynes Grey and Burnt Sienna.
We do not offer a direct alternative to the 'Liquid' base coats but there are many YouTube video's that instruct how to make your own, with the white typically being a combination of Titanium White Oil Paint & Linseed oil.
One useful difference the official products offer comes to Canvases which are primed grey so make it easy to see where a white base coat has been applied. On white primed canvases (standard or deep edge available) or Canvas Boards the wet white base coat can typically be seen by catching the light or if it is a real concern a light coloured Acrylic paint could be thinly applied to the canvas surface and apply the liquid base coat once dry.
Alternatively we offer a range of natural coloured canvases & boards.