Pa-Miw Shabtis Still Sold on EBay

Readers may recall the so-called "Wenneb" (scil Pa-Miw) shabtis that were floating around the market in 2009 and 2010: here , here , here, here and here for example. Basically, there have been quite a number of these items appearing on the market at the same time, one English dealer is reputed to have (had) "hundreds". None of the items being offered for sale has anything more precise offered as a provence than "from an old [insert country name] collection" type provenances. It is believed that there are no examples known in museum collections, or in old auction catalogues. If there had been a legitimate group of pre-year-X exports of a full tomb assemblage of 365+ shabtis being split up in recent years, collectors would have heard of it. And so on.   It seems that seller JFF-Armarna who is based in Homberg, Germany still has some and is flogging them off on eBay.

JFF - Ancient Egyptian Faience Shabti / Ushabti with nice Hieroglyphics
Ancient Egyptian Faience Shabti with Hieroglyphics
Date: Egypt, Late Period, 26th. to 30th. Dyn. c. 664-332 B.C.
Material: Faience
Size: ca. 6,3 cm; c. 2,48 inches
Condition: intact
Provenance: English private collection
Please have a look at my other items!
I GUARANTEE THIS ITEM IS GENUINE. 

This "English private collection" would not have acquired this two years ago would it, along with the job lot  #250600498508 of "10 Egyptian Faience Ushabtis w. hieroglyphic Text, from my private collection ( previously London art market)" with a buy it now price of US $999.00 that the same dealer was selling in March 2010? So in fact "provenance Old English collection" here means nothing more than "the box in my own desk drawer"?

How can this object be "guaranteed" genuine? Who is the seller to offer such a guarantee,? He or sjhe does not give a name nor list any qualifications to evaluate such an item, most of their previous sales are kept "private". As was pointed out earlier, these things vary in both inscription, and here we see it in a different faience from those on the market earlier. There is no known provenance in a legitimate excavation from a known source, there is no collecting history establishing any kind of a pedigree. What actually is JFF's guarantee, and what is it worth?