Vallejo is only maybe 50p to a £1 more here in manc than GW paint, there is actually slightly more paint IIRC and they faact its comes in a droper type bottle means less chance of it drying out.
That all said i'm a lazy arse and still use GW paints, mainly since i paint in GW so often.
Also a lot of the online things refer to Vallejo colours which are quite commonly rip off's of GW ones. Its quite easy to spot which are which i.e Magic blue = enchanted blue
Field Marshall Lord Neil Alister Mackenzie Kerr the Marquess of Lothian
aka Team Scotland 40k Captain 2012