Matty: Sounds like the time to invoke one of my cardinal rules when buying used audio gear: get the seller's phone number and call him/her. You can get more questions answered, faster, by telephone than playing around with E-mail exchanges, with the added "plus" of getting a clearer sense of who you are dealing with. Ask questions that elicit details about the item(s) being sold: condition, how long they've owned unit, are they the original owner, repair history, serial number, any problems they've encountered using the equipment, etc. You can also ask somewhat more personal questions, such as what the person does for a living, where they work, etc. If you don't get satisfactory answers to your questions, don't buy from that seller.
As a final precaution, ask for the seller's work address and tell them that you want to send the payment to them at work. The answer you get can sometimes be informative...
