Yes the SIP are in all the workshop tool catalogs from main parts suppliers.I think it's because the parts suppliers often sell SIP and some will do them on payment plans so they're very accessible for garages.
I have a Kemppi MinArc MIG200, which i love and would highly recommend. It has been flawless from day one, and i've done a lot of welding crappy MOT failure cars with it as well as proper welding.
Will have a look at the Kemppi then, cheers