Retail was always $150-$160, regardless of secondary market prices, and now Luke can be had for $75 (give or take) and Vader for (average) $120ish. They'll go down. Stormtrooper retailed at $150 too and now you can usually get one a t a deal for $100. It's jsut a matter of patience and not buying into the hype that they'll go up. In my experience, they'll go down, FOR SURE. Not all the time, not commonly, but they will show up and you just gotta be ready.
Even the "limited" ones aren't that limited. The 1000 Shadow Troopers or Sandtroopers are ONLY 1000 in the States. There's still more out there. I'm sure Boba and Jango will hold their value for a little longer than most, but even than I bet in a year or 2 you'll find one now and then at an awesome price. PATIENCE is all it takes along with the constant checking of sales threads and eBay.