I don't understand the "need" for buis on a civilian rifle.
What could you ever be doing with your rifle that you couldn't just stop and correct the problem with your optic? No one is shooting back at you and if you're competing then the chances of your optic quitting mid round is pretty much zero. The biggest risk for damage is when you throw it into the safe barrel at the end and if you damage it at that point you would have until the next round to either fix your optic or remove it and install something else.
I have buis on a few of my rifles but that's mostly because they came with the rifle when I bought it and they aren't in the way of my optic. The only rifle I have them on that I might use would be my NR ACR because I have a 3-9×40 on it and that scope isn't much use for close range.
We aren't some special forces GiJoe's and all the crap I see on peoples personal rifles these days makes me laugh. Guys spend all this money on what if's and just in case then hardly ever shoot their rifles. That's why I suggested going with the cheapest decent sights available. They'll probably hardly ever get used and the what if day will probably never come. I suggest taking the $100-$300 you were going to spend on BUIS and put it towards a better primary optic, training, or more ammo.
When I did a CQB course last summer my 1-4 scope lost it's seal and fogged up. I simply kept shooting as I could still see the targets and it remained accurate. When I got home I removed the scope and sent it in for service and the new one was in my hands in a couple weeks. I simply used a different rifle while the scope was gone and if I really needed to use that rifle I would have taken some glass off a different rifle. This isn't life or death stuff here, we have time to fix things that break and it doesn't ruin your day. Spending a couple hundred dollars for parts that are for the most part not needed and most likely will never be used makes little sense to me.
Of course everyone is free to spend their money on whatever they want and dress up their rifle however they want, I personally just don't see the point in spending a bunch of money on something that serves no practical purpose.