You could try any of the RC shops, but usually I personally find the local DIY a cheaper source for tools that I use only occasionally.
If the cheap tool out of a cheap kit wears out I buy a decent version for decent money. For the rest of the kit I don't mind if I never use it because it was "cheap".
Downside is you need to keep a eye on your tools to see wear before it damages your nuts and bolts.
best regards
Olaf