Basically there's one cost item, which is "hire an artist to do the thing", though if I could pay myself for a few days of work to get it polished that would help too.
I'd guess minimum £200 or thereabouts to hire an OK student-quality artist.
If I had the artwork in hand I could have the basic game wrapped up by the end of January, though it would be more dependent on the artist's schedule than my own.