Most groups bidding for the Worldcon have sold Pre-Supporting Memberships, purchasers of which received rebates or reduction of their convention membership fees if the group won.
- Presupporting. A pre-supporter of a bid is someone who contributes an amount in the neighborhood of $20 to the bid committee to help support the bid and especially the bid parties it throws. A successful bit will typical have over a thousand pre-supporters by the time the bid is over. It is common to give pre-supporters who also voted in site selection a small discount (perhaps $5) on the conversion fee to attending member provided that the conversion is done in the first four or so months after the vote.
- Pre-opposing. Pre-opposing bid membership was created as a jest when people who opposed a particular bid still wanted to provide financial support for its bid parties. A pre-opposing membership normally costs twice as much as a pre-supporting membership, but with no extra rights or privileges.
- Friends of the bid. It is common for a bid committee to recruit people from all over to assist in bidding, financially, as help or simply by publicly supporting the bid. Such groups are often called "Friends of the Bid" or, sometime, names which fit in to the bid theme (such as "Aldermen" for one Chicago bid). Friends generally make a much higher contribution than pre-supporters (typically $100 compared with $20). They will also frequently do things help man bid tables or, if local, help buy supplies for a bid party. A successful bid will typically get one to two hundred Friends. Winning bids often provide Friends with a free upgrade to attending member, though Chicago in 2012 did not do this and it is to be hoped that other bid committees will follow suit.
With the escalation of the size of the Worldcon, the number of people who can (and will) misconstrue rights and privileges of their membership type has also escalated, causing some bidding groups to avoid discounts in actual membership rates. (Thus, L.A.con II, instead of Pre-supporting Memberships, sold memberships in a separate group, Friends of L.A. in '84, to support the bid. Friends (and Enemies, the equivalent of Pre-Opposing) got special privileges, buttons, etc., but paid the full membership rate.)
See Worldcon bidding process.