hey deano, where ya been looking?
on my first try at
http://www.spanair.es i found a rt for 144.95 euros leaving on sept. 7th and returning on the 13th.
with the same dates,
http://www.viajar.com gave me a rt as low as 140 euros but then ya gotta pay their ticket issuing fee which brings it in for more than spanair mentioned above.
iberia came in at 177 and change.
so, all 3 of my tries came in under 200 euros.
i'm sure if i kept diggin it would get even cheaper than 144.95.
for the record, i did not think it was that expensive to fly to tenerife in sept.

just a month ago spanair had flights rt for under 80 euros, too bad ya did not reserve then
not sure if you already have a place to stay but have you tried the main travel agency sites? they have package deals with flight+hotel+shuttles for 2 people pretty cheap on a 8 day stay (7 nights).
http://www.viajescrisol.com for example has the trip for 691 euros including rt flights, hotel (half pension) and both airport transports.
try also the following for similar package deals...
-
http://www.viajesiberia.com (THEY HAVE A 2 for 1 DEAL FOR THE ISLANDS RIGHT ON THEIR HOMEPAGE!!! including southern tenerife).
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http://www.halconviajes.com-
http://www.marsans.espersonally, i find these types of package vacations to be a great deal.
saludos and happy hunting,
jer...