Both the the Portamig and the SWP are fine machines, I personally wouldn't bother with the Sealey. I am biased towards the Portamig having one myself, built in York "Britain" and built like a tank, has a low 15Amps so perfect for thin metal welding, if you are not an expert. There are plenty of reviews on here regarding satisfied Portamig owners to keep you in reading for a while. Good luck!
Any questions give Steve a ring at the shop above, a very helpful guy.
Like Tonto above there's an outlet locally selling a Weldability 200E and was wondering if there are any opinions on this machine, how does it compare to the Portamig 165 for instance???
I had a gys smartmig which I sadly had to sell to raise some funds but I will be buying another when finances allow, it's a great little machine which I ran on 0.8mm wire and argosheild on the hobby contract and welded from thin 2cv steel upto prepped 6mm for a repair.
I believe parts are readily available for any repairs also.