1/ The Chinese knockoffs probes are not capable of the specified BW or RT and will proove clumsy and unreliable.
2/ We have used P6137 for decades, they must be treated with care like any probe, use care kinking the cable, dropping or exerting pressure on the tip. They are robust and professional and far less delicate than some other TEK probes.
3/ On epay beware of probes without tips, damaged inner tip, frayed or torn coax.
Sellers that are equipment dealers will sell lots of 2-10 junkers. The tips and ground leads are needed and to trivial to find.
4/ Besides epay, we have found good probes at Ham Radio flea markets and silent key estate sales.
5/ Occasionally you find NIB probes with original accessories and case. Those are costly but the best.
Hope this is of use to you!