Cheap 1/144 Shuttle window masks?

[Michael Morris]

One of the projects I'm looking to undertake is a 1/144 model of Enterprise making it's first landing of the ALT programme.  The original paint job on Enterprise had white window surrounds, so I can't use any of the plethora of decal sets for the shuttle at this scale to provide window surrounds.  The obvious answer is a mask set.  The problem is that the only mask set for shuttle windows I can find are the Newware sets.  However, with postage, these will cost me around £15 - £16!  That's more that half the cost of the donor kit (Revell Shuttle + SCA = £31 on EBay).  Is there a cheaper source of 1/144 window masks?

Thanks