Then a complete waste of money buying a "cheap" one..

And you mention a trailer....will a cheap one even be up to the job ?

Buy the right unit first time. So what if it costs a little extra, it is something that will likely give you a lifetime of service.
So £££ per year, really is a miniscule amount

Ive had my current MIG for over 20 years, and other than some minor repairs, it's given superb service.