These can be bought new from Amigakit for a reasonable price (which is exactly what I did) but I have no use for them now as I don't intend on pursuing with any Amiga 600 project anytime soon.
My A602 Chip Exp and Kickstart 3.1 Rom cost £47.77 together but I would sell them both for £30 plus postage. (Separately would have to be £20 for A602 and £10 for Kick3.1).
They are pretty much new, only being used once to test that they actually work.
Instructions are included.
In regards to a trade, I would give both of these to anyone that could give me a simple 4mb fastmem expansion for the Amiga 1200 (one which adds ram but keeps the PCMCIA slot active).