Hi,
I confirm what south aussie said, i.e. that Vallejo and Andrea are the same except for the brand name.
I don't know about the price, here in Italy one Vallejo bottle costs approx 2,50 Euro.
If you follow two hint you can get very good reults; the hints are shake the bottles veeery well and apply a non acrylic surface primer to your model.
The greatest advantage of the bottles is that they last almost forever, I got some colors three years ago and they are still like the first day.
The greatest disadvantage is that you can't airbrush them.
All in all my suggestion is buy them!
Bye