Yes, you can go too cheap. You will get poor dimensions and weak steel. I don't have time to go into the whole story, but I once bought a Sadlak low profile SPR gas block from Brownells to see if going as cheap as possible had any negatives. It did. But this was an under $20 gasblock.
Cheapest quality gas block is probably BCM, but they use the same external body/profile on .625 and .750 so the .625 is heavier and makes no sense for you.
The Larue is designed with a longer shank for covering up the blemished, unparked sections when you remove a fixed gas block. A normal SPR short profile won't and it won't cover the front pin hole in the barrel left from removing a fixed gss block. It is a specialty item. Midwest Industries makes one that is heavier but only $45 that accomplishes the same thing.
If I was spending up to $100 on a low profile gas block, I would get a Superlative Arms adjustable set screw gas block. They are $100 retail and if you are LE they are about 20% off. They will sell you a gas tube that is specially bent for their gas block which is slightly higher than SPR spec. Worth the few dollars more to get it if you go this route.