Check online swap markets and online auctions that have a bartering component such as Craigslist.com (check under "For Sale" for the Bartering category), Swapace.com, SwapThing.com, Barterquest.com, U-Exchange.com, Trashbank.com and Ourswaps.com. Check for local bartering clubs. Your local Chamber of Commerce may be able to provide you with information on similar clubs in your area.
STOLEN GOODS - Don't expect any favors from Fences. Selling stolen items is going to cost you, so don't expect to get top dollar for ill-gotten goods. Tonila is exempt (actually all Thieves Guild & Dark Brotherhood fences are exempt, but in the vanilla game this just applies to Tonila). Any mod-added merchants who have been made members of the Thieves Guild or Dark Brotherhood faction will also be exempt. Options: -25% to -5% worse prices.