If you're willing to go with the default script initially...
And to learn the scripting as you go...
Both Auto Hot Key and Hot Key Net are free options.

Octopus is also free, but I don't know much about it.

Everything else (to my knowledge) is a paid option.

Keyclone, is $20 once for a lifetime license which is transferable; you'd need one license per computer you want to run it on simultaneously, but if your entire team is on one PC and you upgrade, you can transfer your single license to the new system.
$20 once, forever... is a pretty good price.

IS Boxer, is in my opinion, the software to beat.
It has a wizard, which will get you going.
And a lot of configuration options to change things.
Lax constantly develops it and adds improvements; it works with more games than anything else, and user suggestions are very welcome.
This is $10 per quarter, $36 per year, or $90 for three years... as a subscription model.

Pwnboxer is a popular choice.
But I've not used it (or anything beyond Keyclone and IS Boxer), so cannot comment much on it.
It is a yearly subscription model, with a fair number of updates.
The support is decent on www.multiboxing.com, but sporadic here.

Game Commander Pro is another option that seems to have a lot of features.
The documentation is rather extensive.
But beyond the initial introduction from the author of the program, they're not an active member of this community.

There's good (or great) support for HotKeyNet, IS Boxer, Keyclone or Pwnboxer.

www.hotkeynet.com
www.isboxer.com
www.solidice.com/keyclone
www.pwnboxer.com (www.multiboxing.com)