LUX could be your friend. Often find some decent CE returns for less than ET on other routes. For SH+ routes ATH and IST offer good value from LHR. Getting silver should be possible for around £1k. There are some decent fares ex-OPT at the moment that would easily get your silver and set you up well for gold. The question to ask yourself is what value will you derive from the status. Will you use it or is it just a status symbol?