Due to how many types of roll bars out there, you'll be very unlikely to find a proper fitting half hood stateside. My advice is bite the bullet and order yourself one as you want it, the UK pound ratio is also favorable.
Alas if you're still willing to prod the waters, it would help identify which bar you have now. H1/H2/H3/H4/H5/H6/H8 etc. You being an SV could be H3/H4
Here is a reference
https://www.softbitsshop.co.uk/caterham-classifications-12-w.asp