Honestly?
If you are not sure yet that you will be building still in 6 months - save your money.
The chances are the humbrol airbrush will just frustrate you and then you DEFINITELY won't be building still in 6 months.
Air cans are a poor and horribly expensive way of powering your airbrrush, too. So you will just spend more money anyway.
When you decide to get an airbrush - don't skimp. Spend decent money 50-150USD on a decent airbrush and get a proper compressor or build your own using the compressor from an old refigerator.
My 2cents - but good advice IMO
