Rem SPS .223 - $530ish
New Barrel - $300-$400 (Depends on the maker you decide to go with)
Reamer from Pacific Tool and Gauge (if your GS doesn't have one) - $70-$100
Headspace Gauge - $50ish (I think)
True Action, Chamber, Crown and install Barrel - $300 (Less if you decide not to true the action but I cannot think of 1 reason why you wouldn't get it done while everything is apart)