What do you want to acquire? A C64 with working 1541 drive, or a C128 with working 1571 drive. I'm hoping to find a set at a reasonable price.
What do you want to sell off? i got rid of a lot of my TI carts, so i'm pretty good now.
Do you want to "right-size" your collection to fit a certain lifestyle? See above.
Do you want to get rid of excess doubles and triples? See above.
Do you want to sell recently purchased things that are not so cool now that you have them? Actually, I'm really good where I'm at (my main collection is TI 99 4A gear)
Is there 1 single magical and highly desirable piece you're hunting for? if not a NES Mini, see above- I'd really like to get my hands on a C64.
Do you have too much stuff to fully enjoy what you have today? I don't think so.