Ali, I have a few comments:
Regarding seloger(dot)com, it is good if you are looking for a property, but if you want to sell one, you will find that you cannot advertise directly on their site. If you go to their home page, then click on "agences", followed by "vendre un bien", you have to fill in your details....and then wait for estate agents (selected by the site) to call you! So the estate agents will choose you, rather than the other way around! Not the best way to do things, IMHO.
immobilier(dot)fr is OK, but in the current crisis do not expect much interest, unless you offer the property at much less than the market rate. Advertisements are free.
Florent is right about leboncoin. It is a massive site with a big readership. Advertisements are free and easy to put online. But once again, the price will dictate whether you get any replies.
You could have a look at immogo - just Google the name and you will find it. They have a "no sale, no fee" option, with low percentage commission, which is worth looking into.
However, in the current depressed market I think you may have to bite the bullet and instruct a few local agents. French estate agents normally show their prices as "FAI", meaning they ask a higher price and you get the net figure agreed beforehand. (In other words, the buyer pays the agent's fees, but the price is increased to cover them). Percentage fees are much more than in the UK, so be warned! A cheaper alternative is to go to your local notaire (a rough equivalent of a UK solicitor),who sells houses and charges less fees than an estate agent - thus making your house marginally cheaper than with an agent, after fees. There is also the advantage that he will also handle the sale for you, so all is one place. Many of them, but not all (!),speak some English. It is best to take an interpreter or French friend with you.
Best wishes to your mother in her sale of the property!
Regarding tax (French capital gains on a second home),you are right, Ali. Provided your mother can produce proper receipts from professionals, and the total spent (original cost plus receipts) is more than she originally paid, then she will not be liable to tax in France. It is a sad reflection of the current market that she will bear a loss at the moment.
