yeah, if you want to sell links on a month to month basis for a flat fee, either sell yourself or go through a broker. people will complain about the broker route, but if your site is busy and has a big audience, then it makes sense to sell yourself. if it's not, then why not use a broker since people are looking for ads there. some places are good, some places are ok but if you're selling, my suggestion is to list your site at all the places. link selling is a big thing these days and people who are lookin to buy are going somewhere, so why not make yourself available at every place you can? better your chances.
will.spencer has some good places listed and i have a health site i write articles on and manage that i list on almost all of them. if you have good information and even mediocre google pagerank, you price reasonable and they'll come eventually. some places have good systems in place and some are just buy/sell and thats it.
auction sites for links:
linkadage/com - i think they're the original link auction place, not bad
ebay/com - i read this above, i can't believe i've never tried it there! good suggestion
broker sites:
text-link-ads/com - they have come a long way and have a lot of big sites you have to compete with. my health site is nothing special but has a lot of info, yet i have to compete with huge sites and it's a bit intimidating and i think it caters to the bigger guys/sites. i've been with them for a while and have a few links i make money on every month.
textlinkbrokers/com - these guys are real big on high pagerank sites, so when you show up with your site and low pagerank they want to almost low ball you out the door. they also cater to the big boys. i guess i understand, bigger money for them. i mean, why is everyone reading these pages? we want to make money, well these guys too so i guess i can not fault them.
linkworth/com - this one is by far my favorite and i think its because they seem to cater to the average guy/girl and their system i like. i've been using these guys for a couple years and at my best time i was a little over a grand a month. they've always been nice and helpful too. had a couple weird issues but they were always good to work with.
paidtextlinks/com - not a bad place either and i make a bit of money from them. i signed up with them not long ago so i don't have too much feedback. so far so good.
i'm a bit wordy, but hopefully this helps someone. i make almost 2k per month selling text links so i'm a big fan.
oh yeah, something else to consider is the in-text ads. i make a bit of money from this. i'll make this explanation quick.
intellitxt/com - is the biggest kid on the block. but you have to have a busy site to qualify. i don't qualify.
kontera/com - they also want big sites but they're a little more ready to let smaller sites participate. I do ok with them it just matters on your traffic.
linkworth/com - they just started a version of this and i don't use it but have been thinking about giving it a try to compare with kontera. they call it linkwords.
ok i'm done