Al, those are fun little items, but I think their rarity is open to debate.
The first problem is with Abyss, which, believe it or not, is actually available from the Flying Buffalo web-site
as a photocopy. 
Get your Abyss here
So, basically every interested T&T player either owns the original or has easy access to a copy (literally).
Of the other two, I would imagine Goblin Lake had the bigger press run. I remember it was quite the big deal when it came out, whereas Circle of Ice didn't seem to make as big of an impression.
One thing that might work in your favor, though, is the condition. Most of the Pocket Adventures I've come across have either been thrashed or way short of mint. If yours are in decent shape, that would certainly appeal to the average T&T collector.
Keep in mind that I'm guessing here, but I'd say ... $5 apiece on the low end, $15 apiece on the high end.
