If the gallery is offering to do it for you for $165, 
take them up on it. :)  I am pleased to hear of another
Secret of NIMH collector, my husband and I have 3 of them,
all bought from galleries.  Which gallery did you get yours
from and what characters is the cel of?  When I get my cels
framed, it usually costs me about $200.  In my framing, I 
end up using 4 acid free mats (@$23 each), UV glass and a
nice Nurre-Caxton wood.  I've worked in the framing
industry before, so I know exactly what I'm paying for.  
Really tho, let the gallery do it.  They will frame it well,
put the certificate of authenticity in a nice little pocket,
and if anything goes wrong with the cel, you have some
recourse.  Just my 2 cents. :)

Jen