Hi, Assuming HPS is HPS (there are no variations apart from Wattage) then check out ebay (uk) for sodium flood light Would be awesome if this was the case )
Also just to throw it out there http://www.ebay.co.uk/itm/NASA-Designed-Mylar-Emergency-SILVER-Blanket-Cadets-Scouts-Outdoor-Festival-/261221896820?pt=UK_Health_Beauty_First_Aid_ET&hash=item3cd209d274 Sweet if it is as good as...... I am sure some one in the know will let me/us know at some point.
It is for a mylar blanket, the sort they use after marathons etc, I see a mylar sheet for a grow room