I haven't tried one personally but the $270
Mueller Tac II may be worth a look. Chuck Hawks recently did a review (paid membership required to view) and places the Tac II in the same
league as the Monarch and Weaver Grand Slam. Most Muellers are assembled in China using Japanese lenses (good bang for the buck scopes), however the Tac II is made entirely in Japan and is their attempt move to selling up market products.
I'm also a fan of Weaver products but haven't tried a
Grand Slam personally. However they do have a very good reputation.
A final option is to go down in power a bit. The
2-8x32 Monarch (top) can be had pretty cheap (~$270) and it's one of my favorite scopes and it should match well with a 6.8 SPC. Check with Bud's Gunshop for a great price. Finally a
Nikon 3-9x40 Team Primos (private label Monarch UCC) (bottom) can be had for $220. I own two of the Team Primos. Either of these two, especially the 2-8x32 would be my recommendation.
A note on objective size and light gathering. You can divide the objective by the magnification to get the exit pupil size. Do it for both the minimum and maximum magnification. A 3-9x40 will give you 4.4-13.3mm depending on where you have the magnification set. A 2-8x32 will give you 4-16mm of exit pupil. By the time you reach 40ys old you can't use much more than 4-4.5mm. Of course if you're a sharp eyed young'en you may be able to use up to 6mm or so - for now.
So decide if the extra 1/2lb or so for a 50mm objective is worth it to you. It's not to me.