Here's an idea - this is what I would do (and if you are on any affiliate networks you can do it too, easily) - I'd show them a basic figure showing how much I get per click, across all the clicks I sell, and since I happen to be able to measure clicks within different product ranges I'd also show them how much I get paid per click in their field. Then I'd insist they pay me per click on the text link, not on annual terms. In fact I'd prefer it if they worked via an affiliate network and could track how much money I make and pay me a percentage of that. But even though I can build the tracking for them and give it to them to integrate so that the money I make is tracked, most businesses are completely rubbish at that kind of business co-operation and distrustful and stupid, so it's impossible to get em to do it without going via an affil network (which is why I am actually slowly building my OWN affiliate network - to compete with all the big boys, CJ, clickbank, etc - you name it, they'll all know my network within 3 years - and will be applying to me for special deals I have for affiliate network owners who want more publishers and more advertisers... gotta be nice to everyone if you wanna run thwe game).
I say go for pay per click - if you have a good quality site (which you sound like you do, since the name is cool) you should be able to measure what you get already - if you have no ads yet. Go for 5 cents to 10 cents, I reckon. It's low enough to be taken seriously and high enough to make a lot of money if you have just a staple amount of traffic.
Okay I saw your site. The affiliate graphic ads you have - if you get the new advertiser to pay you the same rate per click as the amount those ads are paying you, then you know you are giving them a fair deal and they ought to be able to see that if you present it clearly. That's what I'd do. It's a good idea, maybe I could print out some of my results and start doing telesales and selling ad space directly! Nah. Can't be effed. I mean, I've reached a point where there's almost no one ever that I actually have to talk to, take calls from, read emails by, etc... why reverse that for a few pennies more that I don't need. I'll pay someone to do that crap later, eh?
Also - Free Tech Support... is a great business idea. I am going to add it to the list of websites I am going to build - a free tech support site. I won't use a forum, I prefer to build my own software, above all if it's interactive. Nice idea. Don't worry - there's room for both of us (and plenty more). Hope my advice helps you secure a good deal, if you use it. I don't know what people are willing to do outside the internet buying and selling arena - i.e. I don't know what corporate advertisers' policy is toward buying per click off an SME. But if you have proof of the value of the click, it ought to be a straightforward transaction. Either they pay a budget in advance or they are billed monthly.