"I've tried the Keil compiler and it is very good but a little expensive for a hobbyist"

That's because it's a professional tool - it isn't aimed at hobbyists!

You wouldn't expect to find hobbyists buying the high-spec Tektronix or Agilent (nee HP) scopes, but you also wouldn't expect professionals to be messing around building their own Heathkit scopes...

It's the same with any tools: if you're a professional, and your business and livelihood depends on it, you don't skimp on the tools of your trade.
eg, it's no use a professional carpenter just nipping down to his local DIY shed and buying the cheapest saw he can find if it's blunt within a week's full-time use and so poorly made that it can't be sharpened!

[refrains from further rant about skimping on tools - even for amateur/hobby/DIY use...]