I just bought a round trip for the Gran Canaria Desktop Summit, flying out on July 3rd and returning on July 11th, with Europa Air, from Lyon to Las Palmas via Madrid, for €254 including taxes. I found the ticket on Expedia.
This is, quite frankly, very cheap - and I expect that ticket prices will only start going up from here on in.
To all those planning on attending: please buy your tickets now.
If you need some travel assistance, buy the tickets now, and keep a receipt, and ask for assistance afterwards. The longer you wait, the more expensive your ticket will cost, and the less likely it will be that we will be able to partially or fully reimburse you.
It might be worth your while checking ticket prices via a travel agency - since this is a holiday destination, the travel agency may have access to charter flights which aren’t listed on sites like lastminute or expedia. Also, have a look at Easyjet, a budget airline that can give you really cheap flights and isn’t listed in the online reservation sites.