It's a great find for sure, however personally I'd be a bit reluctant to purchase the one you linked to on ebay. Three reasons: first, he sells them as 1.5GHz probes when the BF998 is only rated for 1GHz (I doubt they incorporate a 50% BW margin). Second, he changed the design by using different passives - e.g. 5x2M instead of 10M (R1), 51R instead of 47R (R4), 5k1 for both R2 and R3 instead of 4k7 and 6k8, respectively. Capacitors are unknown, so who knows what he uses there, but he also replaced the input capacitor C1 by three capacitors in series. Third, C1 is supposed to be a PCB cap, not a discrete component. Hence, he turned a non-existant component into three existing ones.
I'm not against changing the values as such, they could of course yield better performance. However, the 3x?nF and 5x2M changes make me wonder if he had to "make do" because of component availability/cost in the Ukraine. Not only do they both add significant trace length on the input side (and thus increase stub length and impedance mismatch when probing 50R transmission lines) but also increase the non-linear impedance seen by the signal.
Also, what about the ground return path? The original Elektor design has a direct return where this has... none?
Overall, I'd try out the original design for sure but stay away from the design sold by the ebay auction seen above.