I would agree, your requirements are a little broad.
For clips that are easy, cheap, inside use only, low voltage, and easily user handled, RJ-11, RJ-12, RJ-45 are good ones. Just make sure they aren't mistaken for telephone/ethernet connectors. Connectors are cheap and it's easy to find telephone/twisted wire cable in different lengths already. I've seen RJ-11 connectors used as datalog and in field code update connectors quite often.
Looking back at your requirements, though, 4 pole 2.5mm, seems pretty small to me. Not sure how much smaller you can get.