My local public library has ASM vol.1 in omnibus form, but I have not looked at it since it contained Essential Spider-Man vol.1 and vol. 2. I did a little more research after I read your post and it appears Masterworks goes back and forth through various characters/titles of overall Marvel with half of the material from an Essential volume.
Maybe its this other collection series I am confusing Masterworks with. Epic Collection. I have seen Return of The Sinister Six trade at my local comic shop. However, it seems to skip around. There is also the Alien Costume Saga. Apparently, it skips between titles and collect ASM#252-#258 only from the main one. However, that one may not be under the Epic Collection like the Orgin of Hobgoblin or Birth of Venom( which I own) are just there own thing . Then I would wonder if #259 is collected somewhere.
It helps going in order even if the format is different. It looks like the Masterworks is only up to ASM#202. I am looking for the #250s.
