I doubt it will fit in an entire game.If you had them (haha) you wouldn't be able to put them anywhere, they probs wouldn't fit in the rogue encampment. I wonder how many Els there are in all the realms...(not that you could ever get them all together) ...less than 14,281,868,906,496 I would expect.
14.281x10^12 (a bit easier to write)
http://forums.diabloii.net/showthread.php?t=600073There's a project going on on a German D2 site where members collect as many El runes as possible and cube them to higher runes. So far, the "Das GroÃŸe El-Projekt" has collected more than 35.000 El's and made Thul & 2 Orts out of them.