Should we build our own network of affiliates instead of using software such as zferral? If yes, what are the best value for money affiliation softwares? If not, what are the best value for money affiliation networks?
For a bootstrapped startup, I would answer Yes. That being said, it depends on what you are trying to accomplish...
They are fundamentally different propositions:
The downside for a startup is:
Obviously, I am a bit biased. The reason why we started zferral was because we ran into these issues with our own startups...
I would argue that an organically grown, grass-roots network of brand advocates (zvangelists) is much more powerful (and valuable) to a startup.
Don't build your own, the use of an existing affiliate network will save you time, effort and money. Do not re-create the wheel.
You might want to check Google's affiliate network, if you are an advertiser you only pay for qualified conversions (someone actually buying something from your site) and if you are a publisher then you receive a commission on each sale.
If initial cash outlay is a potential problem, you should start with a simple in-house program and see how it goes. This is especially true if your target affiliate sites don't have a strong allegiance to one of the large affiliate networks and are willing to work with you directly. This is usually the case in niche markets. I've used Post Affiliate Pro software which is very inexpensive and is generally well regarded.
Commission Junction and others like it have their own benefits. You will potentially reach a much larger market and have the opportunity to work with some "super affiliates." That might be the right direction for you to go, but it really depends on your product and your market.
Finally, it doesn't have to be an "either/or" decision. You can run both an in-house affiliate program AND have a program through one of the large networks. Some affiliates will only work with the large networks, but you might be able to cultivate a separate, smaller network with your in-house program that has higher profitability. This way you can work both sides of the market.