My Findings (this is EU centric as I live in the EU, not in the US). Dr Fahey (in Rhonda Patric interview states):
+++Prostaphane (70% bio-availability of sulforaphane) 27€
http://www.cyberpara...hane-bt-30.html
+Avmacol (40% bio-availabity into sulforaphane), c. $30 USD, no EU seller?
http://www.nutramaxs...a-day-p430.aspx
-Thorne Grucera-SGS (10% bio-availability into sulforaphane), $54USD
www.iherb.com/Thorne-Research-Crucera-SGS-60-Veggie-Caps/38994
+Broccoli seeds organic (highest natural amount excl. extracts per g), needs to be broken/blended, needs to have bacteria/enzymes that break this down into sulforaphane, 3€/150g
https://www.amazon.f...rmline broccoli
(+)Broccoli sprout powder (+green bean + cilantro + milk thistle), organic (2nd highest amount in natural products, but bio-availability and product quality varies a lot, most have not been tested for potency!), $19USD (c. €0.50/d)
http://www.iherb.com...-oz-105-g/18638
https://www.amazon.c...i sprout powder
--BrocoMax Jarrow (mostly useless according to Dr Fahey, as it contains almost no sulforaphane)
https://www.amazon.c...i sprout powder
Unknown products galore (there are tons that claim sulforaphane, but only researchers who have tested them, know if they contain any):
https://www.amazon.c... sprout" powder
TLDR; If in EU, I'd go with Prostaphane. If in US, I'd go with Avmacol. If you want whole food, I'd go with organic/biodynamic broccoli seeds (break/blend, do not heat), do sprouting oneself or get non-heat treated, non-oxidized organic broccoli sprout powder (but quality is unknown in the latter).
YMMV, I may be wrong, am not affiliated (nor are any of the links above). All corrections welcome.