Who can rightfully say they have never agonised over a potential deal, only to be beaten by someone else who laid his money down first - only to hear later that they missed out on a deal of a lifetime!
Happens to us all!
Sorry old mate I have no idea the cost of doubles are especially a .577, but if you can afford it & it doesn't appear over priced - go for it!
Otherwise you'll regret it!
Cheers
93x64mm