Are you in the US?
What G5 model is it specifically you're looking at ? This one, the KD i5 one??
Doing a quick search, the price doesn't sound terrible for that particular one, but maybe someone with more recent gaming laptop experience can chime in.
If using Amazon, make sure it's shipped AND sold by amazon. They'll usually cover other things but it can be a hassle. Their return policy for computers isn't great and only covers DOA within 30 days, and if it's a subtle problem like overheating or something they may test it and if they don't see the problem charge you a 15% restocking fee. After that, everything is warranty from gigabyte. So just be aware.