The broad searches (according to Google Keyword Tool) is well under 1000 per month for "iguana tanks", but is slightly above 1000 for "iguana terrarium". Both of those keywords have PPC, albeit low.
I agree with the other appraisals and would say $30-$40.
FYI - IguanaTerrariums//com is available to reg if this is your niche.
All the best!