Always get the best you can afford. Cheap woodturning tools can be an accident waiting to happen.
Sorby, Crown, Ashley Illes or Henry Taylor make good quality tools. Axminster have a range of their own brand which are cheap but quite good.
To get started you could probably make do with about 5 or 6 tools. Many tools can be made yourself. Mainly scraping tools which can be formed from old wood chisels and files.
Axminster do a set of 6 tools for £71.50 which would be fine. A bench grinder is also vital but do some research on what wheels to use on it. A normal one will overheat the tool and weaken it.
Get hold of an Axminster tools catalogue it's full of good woodturning kit and read "Woodturning A foundation course" by Keith Rowley.
I joined a local woodturning club which was a massive help if you don't mind hanging out with a load of old men