Ebay pros: Name-brand clothes will sell well for a higher price than consignment stores -- sometimes a much higher price; the best-sellers on ebay tend to be the new-with-tags; the professional ebayers go around to clearance sales and scoop up whole racks, then sell them on ebay.
Ebay cons: Off-brand clothing doesn't sell as well because people don't trust what they don't know and can't see for themselves; You must take digitial pictures, set up the auction, arrange yourself a paypal account, monitor the auction; once it's done, you must package/mail the items; the fee you pay to ebay and to paypal will cut into your profits
Consignment store pros: Simplicity -- you walk in, they look over your things, and you walk out; no need to mail things, which would really make a difference if you're looking to sell large items
Consignment store cons: The store takes a pretty big cut of the profits, and you don't make a whole lot from each item
And I'll throw out one more option: donate your old items. This won't put cash in your pocket today, but you can deduct quite a large amount from your taxes next year, possibly making donations worth more than selling. You need to keep your receipts, and you must itemize your taxes. Unlike selling, you can donate items that are not perfect, and as far as the IRS is concerned, off-brand stuff is "worth" just as much as expensive name-brands.
