I have an update on this.
She never called me, I decided to call her.
The way she attempted to "explain the differences" was all a bit muddled to say the least.
All she said was that she had a folded one that had a ratings box which is why it was £600. I pointed out that there was an unfolded version on the site for £600 and a folded version for £425.. Nothing else. Her response was that they had "linen backed it". Which I struggle to see what that has to do with prices being advertised for 2 seperate posters without linen back on their site but there you go.
I then said that I have seen this posters sold in the US for around $200 at auction (eMovie), her response "If you think you can get one for under £400 then good luck darling."
She then proceeded to say that they need to make money as well (I agree), and that she's "looking on eBay now and there is one for $190", though she didn't state what condition, whether it was single sided, folded, unfolded etc.
At this stage I just said if you do get one come available please let me know, or I will keep an eye on the site.
Though by the sounds of it they just purchase them from eBay anyway.
Still no clearer on why when I enquired about the £600 rolled version, she proceeded to try and sell me a linen back folded one for £725.. When it was advertised on their site for £425.
All a bit odd, including her attitude.