Hmmmmm.
Well, I've owned over 50 saxes. The best one I've had (still have) was the most expensive, and cost as much as a used car. The cheapest was a vintage Conn, for forty quid (it was a wreck, but still sort of played). In between have been all sorts, but one thing I have found is that, these days, not all super cheapo saxes are rubbish. OK, none of them are as superbly made as my Yanagisawa tenor, and they will never last as long, but some cheapies are workable and durable enough to be worth having. I bought a black enamel Kaeriner tenor, (cheapo Chinese make) for sixty quid off eBay, and I was delighted at how well it played.
OK, that may have been a bit lucky and a bit risky, but I recently play tested a Jericho Alto which was not much more than a G4M, and it was a good sax. Anyone could have one of those, and be confident it would be better than the awful student saxes of the 1970s. And I guess if you were gigging one of these it would be prudent to learn how to replace corks and oil the action (actually, any sax player should learn to do this) but I really doubt whether it would simply fall apart. And I wouldn't call it a piece of sh .... you know what.
(I'm not mentioning G4M saxes specifically, as I've never owned one, but I'd apply what I've said to modern cheapo saxes in general).