Without any driving issues it’s hard to imagine it being critical or dangerous. That does not mean they are not worn and don't need to be replaced, just that it doesn't sound like your car will suddenly explode or anything.
I think the sign for worn bushings is a clunking noise when you go over bumps.
It looks like a relatively easy repair to do. It does require raising and supporting the vehicle and being partially underneath it (at least your arms). If you don't feel comfortable with that than don't do it. Autozone has pretty decent free repair guides (requires registration).
You have to remove the entire control arm and than replace the whole arm or replace the bushings. The bushings have to be pressed out and new ones pressed in. I think there is a tool for this (perhaps could be borrowed) or you can DIY it. I don't really know how difficult this step is. I've seen the bushing around $15 and the arm for $50. So even doing the whole arm will save you money doing it on your own if you can't do the bushing. Option 3 would be to take the arm off yourself and then take the arm to a shop just to have the bushing swapped (hopefully for like 20 bucks or so - more than that and it probably isn't worth it)
$300 for a single bushing sounds like a lot to me. Honestly, with a lift and proper tools I don't see why this is anymore than an hour job for a professional mechanic. Even at $100/hour (which is pretty high I think) it should still be a $115 job. Maybe $300 for two but not one.
I am not a mechanic so please take that into consideration.