For that budget, you are not going to find any OTR brands which are fully canvassed in a staple navy color especially in a 38S which normally never makes it into the on sale section. Even then to fulfill the peak lapel one, good luck.
If you are fine wearing 2nd hand you could continue waiting and there maybe a chance one will pop out. Brand new is not possible, hell at $500 many would already jump at a half-canvassed navy suit in 36/38 OTR.
I think the best option for you would be to get a TaT suit or increase your budget and look again.
Used is definitely an option. I've purchased 2 used suits (one from eBay and one from a user on this forum) and I'm extremely happy with both. I'll keep looking, but I know this is going to be tough sledding.