The decision is obviously up to you.
Have you had other monitors before? Are you familiar with their
husbandry and requirements? Niles & Ornates need lots of space,
heat, humidity and food along with time and dedication.
A healthy Nile can grow to 4' in it's first year under the right
conditions.
To me the Nile sounds ill. MOST healthy Niles, especially a recently collected animal should be very alert, nervous, flighty,
and/or defensive. I am guessing here because no details of it's
history were given - like was it a trade in? If so that may explain it's apparent relaxed demeanor.?
Also, if temps are too low that will cause it to become less active.
If it is a recent WC then it is probably ill and the shop owner
knows this, hence the reduced price. It could have a respiratory infection or digestive tract infection. RI's will
cause labored breathing or squeaking sounds when breathing and
plugged nostrils. The nostril area she be clean - no crust or anything seeping out. Gaping, or breathing with open mouth is also an indicator of both infection types. Both types require
antibiotics to rid the animal of infection. A vet visit would
be imperative.
As I mentioned, more details would help.
Good luck!
E