Trust the Desert_Fox
Prices quoted for a tripod are correct. The POST war ones are cheaper from the US or Germany but then you have to find a seller willing to ship, shipping is pricey and you will pay tax and duty. Could probably find one on Ebay. Try ebay.com and ebay.de
Shows are probably your best place to find a tripod. One at the Edmonton shows recently for $500-800 (and actual WWII production) - sadly it was packed up by the time I sold enough kit to purchase it.
Lafette's can be found. But the prices are as quoted above or more. If you want one I can send you in the right direction (WWII MG34 authentic). My Lafette cost $3000-3500 US and then involved all the other hassles and it was Post War painted and needed a full restoration.
AA sites go for $50-400 ebay.com and ebay.de are a good place to search. There are a few places that sell repro's (excellent quality) so be careful. If paying repro prices they fit the need perfectly, but don't buy a $300 "original - when really it is a repro".
http://www.germanmilitaria.com/ will have expensive but authentic examples and are based in Canada. Many of the big sites in the US (keep shooting, sarco, numrich, IMA-USA) would probably be able to ship this out. Kamabee Keep as advertised in ShotGun News used to have an excellent repro.
Problem is if ordering from the US it is "grey" as it depends on interpretation. They can legally send you a 'tripod' and they can legally send you a 'site' but they can't send you Machine Gun parts. So...which are they???? And do you want to take that risk???
Regards