Web Forum sections to buy/sell links:
DigitalPoint - forums.digitalpoint.com
TextLinksForum -
www.textlinksforum.com
DaniWeb -
www.daniweb.com
SitePoint -
www.sitepoint.com
DigitalPoint -
www.digitalpoint.com
Webmaster Talk -
www.webmaster-talk.com
WebHostingTalk -
www.webhostingtalk.com
DnForum -
www.dnforum.com
Web Sites to buy/sell links:
LinkAdage -
www.linkadage.com
LinkWorth -
www.linkworth.com (I think this is the best)
Text Links Ads -
www.text-link-ads.com
TextLinkBrokers -
www.textlinkbrokers.com
BackLinks -
www.backlinks.com
TextLinkPopularity -
www.textlinkpopularity.com
LiveCustomer -
www.livecustomer.com