Your asking for an aweful lot there.

4.5-14, 4-16, or 6.5-20 are more typical zoom magnification ranges. You may have to be willing to go to one of those. Asking for one in a 50mm objective is likely to narrow the selection even more and also add a few more $ to the price. Fancy reticle is likely to limit options even more and cost extra too.

You have a few options in mid-level scopes.
Your options in a high quality scope are extreemely limited.

In a high quality line, check out Weaver classic V series in 4-16 for under $300 or 6-24 for $300 or just over. Both come in a couple of different reticle options. Though niether is available in 50mm objective. These are premium quality optics with lifetime warranties. I have both of these scopes, no complaints, love'em.

You can also look into Nikon Bushmasters series in 6-18, but that is also only available in 40mm with two reticle options.

You won't go wrong with any of these, but you willmost likely needto make some comprimises. A 50mm objective is atypical requirement in a high quality high power scope.