Sorry, late to the party on this one.
Lego isn't really in the same place a lot of other collecting spheres are, such as SW, Dinky/Matcbox, Horny, etc. Whereas we prize and value paperwork, memorabilia, advertising, etc. the same does not appear to be true of Lego. It is still the sets which hold the value and, frankly, little else. I picked up kilos (must have been 8 or 9 kgs) of paperwork a year or two ago: lots of point of sale designs, shop layout plans, even plans for the shop floor at Windsor Legoland. The best item was the original artwork for one of the Shell promotions on the 1990s: it was specifically the art and design around the shelf danglers. What did I pay? £11. And this was well advertised on ebay. And then she contacted me two months later as she'd found some more and did I want it.
To the point: Whilst this is a curiosity, as Matt says, it's a bit of a niche item. I can see someone paying £5 maybe £10 for it but no more. If it were mint/sealed then I could see it getting maybe £20-£30 but I very much doubt it would get much more unless you were prepared to have it on Buy It Now for months and months.
The Lego world is an odd one. Lego IP is so locked down you'd expect advertising stuff and the like to super rare and sought after, particularly pre-2000 when no-one (frankly) gave a ****, but it doesn't appear to be valued by all but a handful of collectors.
