I had an esab buddy arc 180 it was a nice little welder. Maybe one still dotting about in someone's stock you could get for sub 300 as the new rouge has come out now to replace it.
Haven't seen it any where you might just have to ask around a few places its amazing what gets shoved back in the stock room and forgotten about when the new model comes out. I paid £325 for mine brand new about 3 years ago.
+1 for the Thermal Arc SE 175. First listing in Google search showed it for £258 inc VAT at United Welding. Perhaps cheaper elsewhere. I have welded for years with buzz box welders and fairly recently switched to this one (have also tried a Parweld inverter and they are just not in the same league in my opinion). This truly makes welding easy. Perhaps too easy. It is almost difficult to get a bad weld out of this. Oh yes, and it also does a nice lift TIG function for when I cant be bothered getting my HF TIG out.
As stated, I bought the ESAB Rogue 180pro in the end. Only done a little bit with it so far but it's an impressive machine for the money. So far so good.