I don't mind admitting to writing cheap literature
Can I ask about this bit? There are markets for pretty much every genre of writing, from the pulpy to the obscure, from the pornographic to the chaste, from the sublime (as it were) right up to the ridiculous.
What do you consider "cheap"? What do you write? Does your writing potentially appeal to a current (or future, always think a couple of years ahead) market? If so, who are the agents and publishers that deal in your market?
By 456 manuscripts, I'm guessing you mean manuscript submissions (unless you've written 456 individual books, in which case...
wow) and perhaps maybe that figure is an indicator that maybe a more fundamental change is necessary than the financial.
Agents, at least reputable ones, aren't going to take you on even at 85%. If they went in for that sort of deal - agreeing to handle a client desperate enough to accept it - then publishers wouldn't touch the book with a bargepole.
A more sensible option is to go back to your manuscript. Find an editor to look at it for you, even just a short sample if you can't afford much else. If you don't want to do that, take your writing to a writing group and get some feedback that way. Failing all else, send it round a bunch of your friends and have them read it.
Now here's the hard part - if your friends hand it back and say, "it's great! Brilliant! You should be published!"...
they are lying to you. They're not being mean. They're trying to be nice, because that's what friends do. They encourage one another, and sometimes it's not for the best.
Even well-polished manuscripts have issues. There are extremely popular books out there that are full of errors - typographical errors, plot holes, people who mysteriously change sex or simply disappear - and you can bet your life you've got them in your book too. The reason you can't see them is because while you've been doing your endless edits and re-writes, you've got stuck in a loop.
I can't comment on your writing, because I've never seen any of it. I
do know the mindset of the burgeoning author, because I am one myself.
Harden your heart and take a good, long look at what you're writing. Because it is an absolute certainty that if your writing has problems, then you will never, ever get past the slush pile.
(of course, brilliant writing is just the start - you need to write the right thing for the market, find an agent who is looking to sell in that market that doesn't have a full stable, a compelling pitch, and a whole bundle of luck)
Of course if you just want to see your book printed and don't care about the money, there's always Lulu or one of the other print-on-demand services for self-publishing.