I'm thinking about getting a .458 Socom. Not sure how soon, but I think it would be fun. I've beaked around a little bit for prices but not sure exactly what to get. I would rather not buy a custom gun that some of the manufacturers make, like CMMG, POF and others because they run around $2000 or so. I've seen uppers and lowers for sale between $400-$700 for lowers, and $500-1000 for uppers.

What would be a good middle ground rifle to get? Also wondering if I need to get a beefier lower to handle the round, or if a run of the mill lower would work.

This would just be a fun gun to shoot every now and then, and not something to shoot all the time. Ammo costs too much to shoot it a lot.

I've got plans for one too.  I know it's an expensive and somewhat odd caliber, but I already have plenty of ARs in 5.56.    I'm going with an Anderson lower,  PSA lower parts kit with their upgraded EPT trigger, and  Magpul MOE rifle stock for the lower.  That's about $230 for the complete lower, which I already have assembled and ready to go.   You might be able to get it a little cheaper by going with a cheaper trigger or different stock.   Any lower will work, but I have heard that some people have had trouble with the collapsible stocks collapsing accidentally due to recoil, especially with the cheap ones.  That's one of the reasons why I went with the Magpul fixed rifle stock.   


For the upper, I'll probably go with a Rock River Arms CAR A4 upper half.  That should run about $650 after their 18% website discount. 

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=253

I've read that of the .458 SOCOM makers, it's best to stick with RRA, Wilson Combat, or Tromix.  Some of the cheaper ones have some reliability issues.