Can any art materials make a decent painting? Simply put, no. The quality of your materials greatly affects the quality of your work. Beginners will often say that they will go for the cheapest materials to start with and as they improve, get better quality ones.
The harsh fact is, with the cheapest materials, they will never make a marked improvement. Paper, especially watercolour paper, is one area where money shouldn’t be scrimped on. Real watercolour paper is sized both sides with gelatine; this is so the paint has time to be reworked and specialist techniques can be used before the gelatine breaks down and the paint is absorbed in the paper.
Cheap watercolour paper is not properly sized and is in effect, blotting paper. The paint is just absorbed straight away, leaving you no time to do anything with it. If money needs to be considered then you do not need to go for the expensive cotton rag paper like Arches or Fabriano, just stick to the wood pulp watercolour paper like Bockingford, Cotman or Langton. This is not cheap as such.
An A4 pad of 12 sheets is around £9 but you can use both sides. Unlike food, supermarket own brands of watercolour paper are markedly inferior to the named brands. A tip I will give is to buy a much larger pad size than you need. I always buy an A2 size pad. 12 sheets costs around £22, but each sheet makes four A4 sheets. So when you work out the value, it is much cheaper.
Also, get a decent weight of paper. I would recommend paper of at least around 300gsm (140lb) as this will take quite a bit of water and is a good all-rounder. You can even use it for acrylic painting or pastels. Brushes and paints too will also have differing qualities so don’t be swayed by price. Stick to reputable brand names or ask your local art shop for advice.