there is a regular stream of Boer Mausers turning up in the UK. Typically, you could expect to pay $600 for a ZAR rifle, $800 for a carbine or OVS rifle, and up to $1600 for one with elaborate buttstock carving. Add the shipping to the USA. You will hardly ever find one with a good bore (they were all extensively battle-used and not cleaned in the field) and never one in mint condition. If those prices are acceptable to you, I'd be glad to send you details of some which are currently for sale in the UK gun press or websites. Within a few months I am sure you'll get one.
"The past is not dead. In fact, it's not even past". (William Faulkner)