and where @ 50 for each? assuming matter cab 50 farm pygmy goblin ? and what about 50 nec? which is faster/better for straight gold farming? also I've never done salvaging , is it an absolute necessity for farming?

Necro = stand there and pull mob after mob. no downtime ever, spam a couple buttons. Any spirit weak mob and you will dominate

Cabby = pull whole camp, dot, run, repeat. Gobbos is easy at 50. all con blue. Not a lot of gear drops, so salvaging is lessened a little

Salvaging is a must or you can't farm. If you went for straight gold, it will take you exponentially longer to get the money you could from even just 1 salvage session at 50.

Salvaging at gobs isn't that bad though.
But keep in mind that pygs is overcrowded 20h/24h while necros have an infinitely wider range of possibilities spot-wise.
And yes, if you want money level up salvage, no debate ! (going tailor + leveling up metalworking aside is the cheapest and easiest way)