I regard $400 is "high", not medium. For that price you have LOT of those "higher end" line ups from Weaver, Bushnell 3200 or 4200, Sightron II, Browning (made by Bushnell to 4200 sans "rain coat" or whatever the coating), etc... They do offer great scopes in that price range .. and I have never owned one at that price range. heck.. you should be able to find a new or used Leupold at this price range.
Case in point, your $400 can buy you very nice scopes (none mine, just data points):
* Elite 4200 8x32 AO :
http://www.rimfirecentral.com/forums/vbclassified.php?do=ad&id=28428
* Leupold VXIII Mark
http://www.rimfirecentral.com/forums/vbclassified.php?do=ad&id=28421
I'm a poor guy with limited budget, to me Medium is $150 ~ $250 line up:
* I have Redfield 3-9x , Accu-Plex. Good and honest glass, no gimmic, assembled in USA, I like it a lot. They have a 4-12x in this price range.
* I have a Meuller APV <$110, I see it as low-end price with Med-end quality.
* I have owned a Burris 2-7x, very good glass, just didn't their zoom.. the whole ocular piece turns -- can't use a flip up cover. but if it doesn't bother you, they have GOOD products which also fits your wallet.
* I heard about Vortex DiamondBack is a great scope, but never have owned one..
* I have Weaver 2-7x .. good glass for sure.. they tend to carrry a higher price tag too.
For the price range you have, you should include Sightron II, Clearidge, leupold, in your shopping list.