Don't set a price for certain kinds of transactions, for example:
exchanges (unless a balancing payment is requested or offered), donations, meet-ups, friendship listings between individuals, ...
It isn't possible to post an auction listing for certain kinds of transactions, such as:
exchange listings or grouped exchanges (unless a balancing payment is requested or offered), grouped listings looking for
offer, request or exchange partners, donations, meet-ups, friendship listings between individuals,...
For real-estate transactions, and depending on the laws in force in the country where the site is used,
the deal must be finalised through a notary. Do not make or receive payment beforehand.
You can make a donation by posting an "offer" listing with a price of zero euros, specifying,
if you wish, what kind of individual or organisation you'd like to donate to.
For a real-estate listing, don't confuse the size of the house with that of the land...