I know Tortoise SVN is best for Windows, but what about for Mac? I’ve looked at a few, but so far the nice ones cost a fair bit, what free ones are out there and which are best?
Syncro SVN shareware
You've got a few free options available to you:
SmartSVN - a cross-platform solution that will work on Windows, Mac and Linux.
pysvn - another cross-platform client, free of course.
SCPlugin - Mac-only, integrates into Finder.
SCPlugin was inspired by TortoiseSVN, so if you're a fan of that one then maybe give it a go!