Wilkingson sell a teak dye and teak oil. I've used Wilkingson's own brand stuff before and it has always been good stuff.
The beauty of the above is that it can be wiped on rather than painted on.
They also sell a teak stain which is a mixture of dye and varnish. Could be worth pursuing.
250Ml of dye will go a long way.
Of course, the final result will depend on the colour of the wood you have and the amounts of coats of dye applied.