Just sold a nokia 5800 on ebay for £142 inc RMSD (I only allow special delivery for phones). After delivery and fees I retain £126+. Already communicated with the person, good feedback with expensive items sold and a good grasp of english.
Would never have got that on gumtree for example.
You just need to ensure that you deter foreign bidders, by making it absolutely clear you won't post abroad. Also find the going rate and use a Buy-It-Now. You pay much less in fees and if it doesn't sell the insertion fee was only 40p for me. The other benefit is that if the person doesn't pay or tries to get you to send it abroad, you can just relist it and get a refund of the final value fees.
I do have the benefit of not having funds being kept in arbitration for 21 days since I've sold a dozen phones in the past.
Good advice from Stevie P as well. Just go through the filters and select the relevant sensible options.