The cheapest part of owning any animal is the purchase price. It is always my practice to get the best animals I can, and if that means spending that much money on what is a sure thing (adult or near adult show quality birds) then by all means it is likely a bargin. Hatching eggs from those lines certainly doesn't mean you will only get birds that meet the standard. You're buying birds that have been grown on and DO meet the standard. In my opinion, if those are the birds you want and you want to exhibit, buy them.
It costs me over $100 to raise a large breed rooster to maturity.