There really isn't much to be said about prices for Trilogos, in many cases you simply can't compare one auction to another. Might be the same character on the same card variant but one will sell for £40 being a c8 and the other will sell for £140 because it's mint.
Same for reasonably rarer figures, sometimes you see them sell for less than £100 then you see them go way over.
This year alone I saw three different Trilogo ERG's (often cited as being in the top 10 rarest Trilogos) the ending prices were all over the place: $482, $810 and $1,001...
Back to your question on the Stormtrooper and Boushh- You can find both with some patience, Boushh can sell for a good amount because people get tired of waiting for one to come up, yet just like Ackbar (another unrecognised tough one) you don't see 1 on ebay for ages then 5 come up at once. I saw two ungraded Ackbars sell for £125 and £371 (
) yet I know where there is a very publicly advertised AFA 80 for less than £125 *SHIPPED* - what I think happens is, people can't find certain figures for ages, then splurge the second they find one, only to see another few listed a few weeks apart. They often get cheaper as the market gets saturated because it means less people need them so won't pay / bid as much.
End of the day people will pay through the nose for quality MOC, no dents, no creases, no sticker tears etc, if you settle for a C7-C8 range (displayable but not insanely mint) you can pick most of them up on a smaller budget.
Only the most anal collectors bankrupt themselves on toys