We get avacados in the US regularly. Prices range from < $1 US to $1.50 (at least in the NE). What is your Euro price?
Try these few things... jalapeños or similar green chili, cilantro and "fire" your onion. By "firing" I refer to a Mexican technique in were you cut onion and soak in water and a splash of vinegar. This pulls the oil out of the onion and leaves all the great flavor, but removes the sharp offensive bite. Try it, it's night and day.