Like Gurney, I use the TradeMe website, a local New Zealand auction site, very professional and well sorted.

Have bought three guitars - a Tanglewood TW900, a Sigma D28-12R and a ColeClark FL2AC. No problems with any trade and the goods were exactly as advertised.

The ColeClark was in effect a new guitar in perfect condition which I got for about $600NZ under the local list price in the shops, and when I opened the case, I was blown away by the delicious smell of new wood.

The Sigma was a Japanese made 1982 model, advertised as having some small dings on the headstock (it did, but they were very small). The neck and body were flawless and it sounds great. Apparently it's an exact copy of a Martin D28-12, the R standing for rosewood sides and back. The top is one-piece spruce. It is the loudest guitar I have ever played and certainly the nicest 12-string.

I have also used TradeMe to sell two guitars, an Ovation Celebrity 12 and a Walden. Both trades went just fine.

I think the trick to using auction sites is to be very clear about what you want and how much you're prepared to pay for it. Don't tip off others by making your interest known at an early stage, leave bidding to the last minute. However, don't neglect the "Buy Now" option if the asking price is within your zone - I sneaked a very good brand-new surfboard because the bidding had got within $25 of the buy-now price with a few days left to go.

TradeMe has another useful feature, the "watchlist". This will give you a notification that the auction on your item is due to close in a predetermined time. Also, usefully, sometimes people who have put the item on their watchlist will be contacted if the item fails to sell in the regular auction and you will have an opportunity to put in a lower bid: which is how I got the Sigma.

And certainly, read the seller's reviews carefully, but don't put your faith in them. And yes, pay for insurance if you're having anything shipped to you.