Good used sendaro stock is normally $100-125
PSS stock is about $150
Costs exactly the same to chamber for 280 as 280 Ack Imp, so do not spend another $100 later to make it an Ack Imp if that is what you want and you are putting on a new match barrel. Do it the first time.
True bolt face and lap lugs -$75-150
Pinned recoil lug (Holland or Tubbs) installed $50-60 (must for switch barrel)
Skim bedd the Sendaro stock -$30-60
used Sendaro take off barrels -$60-100 depending on caliber. Call gunsmiths that build custom rifles
, Tooley, Baer, Holland, Borden, Myer, etc, most will have them laying around and maybe stocks. Do not know where you are at, but if you tell, then someone can let you know who to contact in your area.