Lucky for you, I have guides for all of those books so I know the alternatives well
Secret Warriors: SELL! You can replace it with a pair of complete collections for about $45.
DD: Use caution. The trio of Bendis Ultimate collections come in and out of print like a revolving door, and if you catch a bad time the price jumps up to $30-40/ea purely due to the temporary scarcity. I've watched this happen at least twice since 2014. The Brubaker trio of Ultimates can be done for under $70 but miss a pair of omni-only issues (which you could buy floppy and get custom bound and still make out on the deal).
Cap: SELL! As of about a year ago, the Brubaker Run can be covered entirely with PHCs which all hit bargain bin, plus a set of initial Ultimate collections that taper off. I put together the whole run from front to back averaging well under $3 an issue.
Punisher: You'd need to specify which one, and I don't keep track of the MAX stuff.
Uncanny X-Force: SELL! Though I love and cherish this Omni as much as Astonishing X-Men, the pair of complete Collections can be had for under $60 combined, plus you can pick up their Fear Itself book, which is the only UXF appearance outside of their own series.
Iron Fist: SELL! This is a no-brainer - the first Complete Collections is equivalent to Omni, and the second gets you the entire series.
Cosmic: Depends. Annihilation stuff was already expensive pre-Omni, and I haven't checked to see if it came down. Plus, it's only going to get MORE ridiculous as we barrel towards Infinity War unless there's a reprint. If there is one in your set I'd keep both for being solid collections AND for potential future upside, it's probably these. That said, I've been happy to have it in OHC instead of Omni - you could find a deal that would make the switch worthwhile.