So you want to sell your guitar on ebay? Great way to do it!!
Your only other real options are 1) put an add in the paper, 2) Sell it to a pawn shop or 3) See if a music shop will buy it off you.
Well!! More people interested in buying guitars will see your add on ebay, and they will pay you more for your guitar than any pawn shop or music shop!
In fact a lot of music shops and pawn shops sell their guitars on ebay, not just in their shops because they know they'll get more interest and a higher price for their guitar!!
Well known (collectacle) guitar brands such as Fender, Gibson, Ibanez etc, are well know buy hundreds of thousands of people in the market for guitars, and they know what your guitar (or a very similar guitar) is worth somewhere else - much like an insurance company can look up your 1998 model Ford and know exactly what to insure your car for. Collectors (and there are thousands on ebay) will always bid up to the market value (the price that they are sure it is worth today) so you know you will get a fair price. This allows for two things: 1) you can safely list your guitar for 99 cents to generate a HEAP of watchers on your item and 2) not only will you get the market value price for your guitar but someone is likely to FALL IN LOVE with your guitar for whatever reason and go above and beyond this price!!
As an example, the fender I bought 10 years ago for $500 (US) just sold for (US) $840.