(Non-Sports) Best Way to Value This? Golda Meir/David Ben Gurion Dual Signed
 

I have seen various images signed by Golda Meir and David Ben Gurion sell for a few hundred dollars.

I bought this a few years ago on eBay for a few hundred dollars as well, but think I got a steal (I do not recall if I bought in an auction or buy it now for a fair price).

Is the whole of this piece merely worth the sum of its parts, or could it be worth more? I have not found any pieces signed by both of these highly influential political figures.

Any advice appreciated.

http://i63.tinypic.com/166tsi.jpg
http://i63.tinypic.com/2d7avj6.jpg