Hot.wire and others were around $35/day. Tested the waters with $15/day for a Full Size - just out of curiosity, since I haven't done this for a while. Got counter offer for $33.
Started another bid with $25/day for a Standard Size - got counter offer for $31.
Rejected this - got a "one time re-bid" offer - tried $27 - got rejected and counter offer again for $31.
Since I rather wanted a Full than a Standard (they sometimes come with GPS included) I didn't mind the $2 more, so I went back into my rejected bid for a Full Size and booked it for the counter offer of $31/day.
Moderators: This may be something for others to note permanently - or maybe it is already somewhere:
If you got a counter offer, you don't have to accept it right away. It always stays in your "trip history" as rejected offer. If you open it from there for review, you can still book the counter offer, even though you rejected it originally to bid again below it.
Cheers,
Georg