This is definitely the most simple of the display solutions I have worked with.  The LedBorg is also the cheapest (especially if you live in the Uk where shipping is free). It'll set you back just £4.99

With the LedBorg

I now have ISS-Above working with the LedBorg – a tiny add-on board that displays up to 26 very bright colours*.  This is a very inexpensive board (especially if you live in the UK) where shipping is free.   It’s just £4.98 from PiBorg.

LedBoard by PiBorg*note: as this is a UK product… I am using the (some would say) “correct” spelling of color :-)