As Mike Bailey asked: From experience I made it a habit, never to assess any gun I did not handle myself. Here I have to go by the photos and desriptions only, so I will remain vague.
The first Mannlicher-Schoenauer is a Steyr factory take down, in fact detachable stock, variant of the M1903. A 1929 Steyr catalog called this the "English Sporting Pattern". Standard features: Single trigger, hand detachable half stock, optional peep sight to hand of stock. The modern Swarovski scope was obviously mounted quite recently, using a hand-made mount. It is apparently a side swing mount, the rear base design inspired by the 1960s Steyr factory scope mount offering. I have seen many more elegant mount systems on M-Sch rifles.
The G.Gibbs Mannlicher – Schoenauer # B5433 is a typical product of that gunmaker. Gibbs then imported Mannlichers and Mannlicher – Schoenauers from the Steyr military production and sporterized them to various degrees. Steyr started to offer their own sporters in 1905 only. The rifle closely resembles my own Gibbs sporter # B4842, dated 1905. The bolt handle was replaced on mine. On Holt's one someone merely ground the stem of the military handle to clear the scope.

Even the modern aftermarket German EAW side mount is the same. Forget the 1970s – 80s Jap made "Kassnar" scope. It adds nothing to the "value" of the rifle. The Gibbs takedown system works like this: You need screwdrivers, or rather turnscrews, for takedown. First remove the screw holding foreend to barrel. Take off foreend. Turn out the front connecting screw. This goes into a recess in the barrel threads and keeps the barrel from turning. Now you can turn the barrel out of the receiver. This system is fine with open sights that are fixed on the barrel, but as the barrel threading and the locking front connecting screw develop some looseness soon, it is less than ideal in combination with a scope mounted on the receiver. On my rifle I blocked the takedown feature with permanent Locktite.
Now to the estimates: British pounds Sterling 700.- to 900.- are to be understood + buyer's premium + VAT. So it's really Lbs 910.- to 1170.-, according to Holt's own "Total Price Calculator". That would be Euro 1300.- to 1670.-, without shipping costs.
Here in Germany half stocked Mannlicher-Schoenauers were and are less popular than full-stocked Stutzens. On German egun internet auctions pre-war M-Sch rifles usually go for about Euro 450.- to 800.-, depending on condition, German scope and claw mount. Full stock Stutzens are a bit more expensive, 500.- to 1200.-, depending on chambering, scope, mount and condition again. You may add some hundred for the G.Gibbs address on the second rifle.
So Holt's estimates don't seem to be exactly "bargains" to me, but the American and Australian market is very much different from the German one. These are auctions, so I hope someone will save the photos and post the end results.