I am interesting in hosting my own forum,
It seems nearly all the forums are used by the same provider as nearly all have the exact same format and just look slightly different. I.e sitepoint/dp etc.
What is that forum provider?
Secondly,
Does anyone recommend any free forum providers or is it just not worth going down that route?
SitePoint uses vBulletin which is a forum script you’d have to buy if you want to use it.
There are a whole lot of free forum scripts that look similar to vBulletin on the front end but which do not have quite the same back end functionality.
Exactly how your forum looks depends on what theme you apply to it. Most forum scripts allow a variety of themes to be applied and the popular forum scripts have many thousands of different themes available that have already been written that you can choose from.
You should do some research on the current vBulletin situation. There’s been some serious talk about the direction things are going with the new version, pricing changes etc. Not a lot of the faith of old customers remains intact.
I personally prefer Invision Power Board. Very good and easy to use forum.
and as a host if you are gonna host your own you should consider using a vps.
Its more secure than shared hosting plus you can customize your own security 
Hope this helps.
vb, smf, mybb etc all are good. however i like vb over others for the support reason.
Vbuletin-fans forums has section for the web hosting discussions. That would be useful for you to do the search there.
vbuletin iwas designed to be used and this forum software does not have any specific web hosting requirements so any php/mysql web host will support that. What to chose shared web hosting account or VPS or dedicated server depends on the size of your forum but not on forum software
I believe that will work on any linux/windows shared web hosting account. Just try to find something you can get afford. Then you might need to upgrade.
vBulletin is actually a little resource intensive and so even a few users may cause it to exceed the capacity of a shared hosting account.
We are using ‘Snitz Forums 2000 Version 3.4.06’. This is slightly different look and easy to maintain. A very light script as well.
Good luck
Its good that you are impressed with the Stepoint looks and the script it is using, it is actually very user friendly. I would recommend you to try something unique and exceptional to get success
This is true.
Make sure you speak to support before you choose a web host to make sure they can handle it.