We use Protech clear stands in the hundreds, either from
here, or BibyCo in Aus (usually depending on other purchases being made at the time).
US$70 for 200 is about what I usually pay.
Unfortunately, my favourite were Real Stands (
http://realstands.com/ ) as they had two pegs per stand (which helps things like Battle Droids stand up), and a more subtle shape to the base...but they're not made anymore

They show up from time to time on eBay, but not cheap.