The pictures are not great, but based on
hard box case
engraved removable bell
High F#
Is say it was a 520LQ. Its not a 521, they have the "big bell", which this doesnt.
HOWEVER THE PICTURES DONT MATCH!!!
look at the shot of the whole thing, the right hand pinky F# key is oval (as on my 520), but in the close up it a round typewriter button
OVAL aux F#, cant really see the engraving, but this looks like a 520
Round F# button...not sure what this is!
Also on the other picture the bell brace looks like it has sort of a rounded rod section, but Ive never seen an Antigua with anything other than a flat plate section to the bell brace, so in short the pictures dont add up.
I'd seek clarification and fresh pictures, but with 2h left if it stays at that sort of price it might be worth a punt on it anyway. I wouldnt chase it too far north of $200 though given the uncertainty and general value of these horns, and the fact that there are usually one or two a week come up on ebay.