correct response is some version of the following.
X date works for me for a party. I will send you a list of people I think should be invited. Please send me your list as well.
Given our current situation, I prefer to have the party somewhere more affordable (our house, xyz park). Please let me know the cost of the party when you find out and do not commit to paying anything for this location until you and I have discussed and agree on the cost and date.
When the men on the chessboard Get up and tell you where to go; And you've just had some kind of mushroom And your mind is moving slow; Go ask Alice... I think she'll know.