As for budget of snowboarders vs. skiers - I think its much cheaper to snowboard. Top of the line snowboard boots cost what, $400 maybe $500? My skier buddy (actually, most of my friends are skiers here) just dropped $1700 on new boots. $1700. That's more than my rent in the Denver suburbs combined with my seasonal rent in the mountains. High end snowboards cost $600-700, almost all skis cost that much. Bindings are super expensive for skiers as well. Shit is crazy, actually.
You certainly can buy boards much more expensive than $600-700, that's probably the top of the mid-price range.
On average though I'd say you're 100% right. Most people pay $300-500 for a board, $200-250 for bindings, and $200-250 for boots. So $700-$1000 for a complete setup I would say is AVERAGE.
Skiers probably pay close to double that on average.