Just go to Gabarino or Fra Vega, and look, in person, at the models in your price range.
That cheap, they are all pretty much the same- painted steel, wire grilles, cheap plastic knobs.
Nobody is magically going to make a $2000 peso stove for $1000 pesos- steel is a commodity, price per kilo is the same worldwide, and it just costs what it costs.
$1000 pesos is not "cheapish"- it is absolute rock bottom, low as you can go basic, no frills, el cheapo.
The differences at this price level are pretty minor- color, layout, type of burners and spiders.
Luckily, if you are buying gas, there isnt much to go wrong- its simple mechanical stuff.
Even the electric ones are pretty basic, and dont have much to go wrong.
I have gas, so I dont know about the electric ones, but I do know that the brands I actually trust to some degree are not that cheap- I have had good luck with Ariston, and with Spar, but both are more than you want to spend- the Spar is argentine made, but a subsidiary of a Swiss company, with better design, looks, and quality, and, of course, a price to match.
In this category, you will get exactly what you pay for, and its unlikely you will find better prices, or a better selection, than at the big chain stores. Plus, they deliver, will do Cuotas, and have those dapper young salesmen with the white shirts, ties, and lots of hair product...