That's extremely expensive. Try McMasterCarr.com and see if you can't find something. Their online catalog is a pain, but if they don't have it there'y not a use for it.
Unfortunately, McMasterCarr does not ship to Canada unless it is with companies they have been dealing with for a long time (before the policy change to not ship to Canada).
I live in Canada, everything is expensive :P
Tank is 20'' tall. Perhaps I shouldn't add the reflectors then, the only source of carbon I was planning on adding was DIY "Excel".
Would you recommend just installing the bulbs into the gutter with no reflector then?
If you are trying to maintain a lower light aquarium, then I think the reflectors would not be necessary. T5HO bulbs put out a lot of light.