I think a big factor thing hurting Rancor Pit's sales (and price) here in the US is that you can't buy Jabba's Palace anymore. I think once the Pit goes EOL, it should shoot right up to US$70 or $80. But, I'm new at investing so my forecasts should be ignored. (seriously)
But speaking as a buyer, I can't imagine buying a Jabba's Palace without a Rancor Pit. My son wanted Jabba's Palace for his birthday (about 2 months after they completely disappeared... thanks again, son), so I went on ebay and ponied up about US$140 for one, and immediately thought, "How can I buy this without getting a Rancor Pit? You know he's going to have the Palace finished about 10 minutes, and then he's going to start asking for a Rancor Pit... What's going to happen when Jabba pulls the trap door? Luke is going to take 1 step down to the surface of the table below and just stand there?" So of course, we got them both. We built the Palace first, and it's great - no question. Then built the Rancor Pit, and I was surprised - it's quick but a fun build. As you're building it, it has a certain satisfying "sturdiness" about it. And the play features are great too.