Those are huge claspers! I agree that this is a red retic. I think the spelling you're looking for is "caqueta", which is the collection region in Colombia. These red retics aren't very common, but I've heard that the red color fades over time and they end up looking like a normal retic. As far as price goes, I believe George @ sharkaquarium sells 7" red retics for around $130, so you can use that to decide whether you got a fair price.
BTW, the ray that Ming posted belongs to redtailfool, which is why the tank might look familiar