If you have a full ecommerce store you could pay a percentage of the sale as well. You may be able to get away with offering cookies so that affiliates sales will be tracked after the initial visit. This way you could pay less per sale, with the potential of the affiliate making money on multiple sales over time.
References :
http://spikeaffiliates.com

In response to the first comment:

No it will not increase your sites "popularity" as the network redirects a link through them and internal programs will be penalized by Google, etc…. if they are not using a nofollow tag to let the bots know that this should not be a backlink.

Plus most affiliates will add in a nofollow piece to the urls to prevent you from getting an SEO boost on their expense giving you an advantage within their niche making it uneccesary to have them.

To response #2:

There are costs involved, you pay on each sale, you pay network percentages, start up fees, man hours fulfilling orders, labor charges monitoring for trademark bidding and adware users, as well as time spent recruiting real affiliates who do not try and cheat you using adware and scumware.

The benefit they were trying to point out though is that after incurring all of those fees, you now only pay when a sale is made. However if the sale is made by an adware user, you are now paying when the affiliate does not even earn the commission, they just steal from you. To prevent this you will need to hire firms which can manage programs for you and will protect you from these toolbars and adware installs. The firms that will actually care about you are few and far between. A couple I trust to do this are:

http://www.affiliatefairplay.com for adware removal
http://www.downtownecommerce.com for full management or cleansing or co-management
http://www.affiliatecrew.com for co-managing a program

and a great place to get a further education on this scumware and cheaters is http://www.abestweb.com

Also, the affiliates that will avoid your program for paying less than 50% commissions are probably not good affiliates anyways. If you want the ones that move products and can generate sales on actual physical products in a legitimate way, you will want to use a network like Share a Sale or Performics, or Commission Junction or Linkshare.

Now be very cautious on the network as most of them will push adware on you and list adware affiliates as their top performers on their homepages.

This is just my opinion, but avoid Click Bank if you have a product you want to move and join an affiliate network and not a CPA like CB. Also, percentages work at 2 and 5%, it depends on the industry. 3-5% is great for electronics, 7-12% on clothing is good, 5-10% on sporting goods, 6-12% on contact lenses, etc….

I hope this helps you.
References :
http://www.downtownecommerce.com
http://www.abestweb.com
http://www.affiliatefairplay.com

It’s no-cost because you only pay for results.

FYI: Most affiliates will not consider a program where you offer less than 50% of a sale. Just check out the clickbank marketplace for tons of examples (they have like 11,000 products and 100,000+ affiliates)

It will only be effective if your business is already effective at closing a prospect (right away or in the future).

Affiliate marketers are business people and they will want to have a good ROI to continue sending visitors to anyone.

The way it works is:

1. You test and improve your website until it has a good ROI.
2. You setup the affiliate program (with lots of sample advertising)
3. You get affiliates
4. Affiliates send prospects.
5. You capture prospects as leads or clients
6. You follow-up with leads and clients.
7. Repeat steps 1 thru 6

HTH and have a great day!
Mark
References :
5+ years marketing online

http://www.clickbank.com