Well, first ask her if she likes limited editions 
or not.. that might help =)

But if it is a surprise gift, go with your gut 
feeling.. =)

My opinion is that some limited editions cels are 
great. I have a few. I also have lithographs and 
those are also very nice. I am quite open minded 
on this topic though. I have my share of great 
production cels and sketches, post production 
cels, hanken, and other anime art. This includes 
cheap cels, mid-range, and high-end. Why be 
limited?

It's all good to me.

And if you gave a gift from your heart, why would 
your girlfriend hate it? It is very nice that 
you've thought of her hobbies and passions,
and your original gift may be a nice touch to her 
collection. She, after all, is not shelling out 
the bucks! 

 In any case, find out what she collects and see 
if that helps out your selection process. The 
closer you get to her "dream cels" the more 
points that you might score. Then again, cel 
collecting is a very personal and "beauty is in 
the eye of the beholder" type of activity.

I hope that helps-- some =)

E