I’ve been researching them for a purchase also.
Best I can tell the Howard Leight Impact UVXR-01526 is the best for the buck. $50-60.
They are slim enough to use with a rifle. The downer of the Peltors. Oh, the Peltors have 2 volume controls, annoying.
They don’t attenuate as much as a good pair of muffs though.
I’ve seen some very expensive models but $200+ for electronic muff is too much for me.
+1 on the Howard Leight’s. I’ve been using them for the past few years on the firing line at Appleseed shoots. They offer very good protection at a good price, even when you’re next to shooters with centerfire rifles (.223 & .308).
A good review is posted here: http://www.amazon.com/gp/cdp/member-reviews/A3974DN8X4ZGTX/ref=cm_cr_pr_auth_rev?ie=UTF8&sort_by=MostRecentReview