You can buy a set of 6 or 8 turning tools for about £25 but, as for those vevor etc lathes, these are best avoided - complete rubbish. If buying new, expect to pay around £25-£30 for a skew chisel or parting tool. A bowl gouge will set you back around £60. I'm not suggesting you buy these, just giving you an idea of the prices. If you can go second hand then fine, you might get HSS (high speed steel) or you might get carbon steel which are cheaper but don't keep their edge for so long. That is not to say they are no good, I still use my old Marples tools regularly, alongside my HSS ones. As to what to buy, well a spindle roughing gouge (ground flat across), spindle gouge (ground into fingernail shape) and a parting tool would be a good start for spindle turning. When you are ready to try bowls etc (i.e. with the grain running parallel to a facepate) then don't use the spindle rouging gouge (not safe). Get a proper bowl gouge.
One of the best things you could buy in my opinion is a copy of Woodturning - A Foundation Course by Keith Rowley. And as I said previously, don't ignore dust extraction.
K