there's a few buyers at most horse auctions who buy horses for slaughter, fewer all the time tho. At any horse auction you will find good horses cheap. take someone along who knows what they are doing or gamble on what you get. all auctions of any kind are a gamble to some degree.
don't be afraid to go look and come back and tell everyone what you saw.
edit (another pay attention kiddies):
there's a registered breed auction hear rolla Mo very soon, do a net search and you will find it. i've sold horses at that barn and bought horses there. go look and take your money with you. you will see many very very good horses sold dirt cheap. their owners will sell many of them for various reasons but very few will lie about the horse they sell, those not being honest you will probably notice easily.
there will be buyers there who buy horses that are profitable to slaughter, that's life. be glad your horse has laws to protect it if you think it wise, no other farm animals do. it's not helped many horses. it's hurt a lot of horses. i'll repeat, a lot of horses.
go to horse auctions, net searches will let you know where and when they are.
last fridays of the month is the Springfield, Mo horse auction at exit 70 on 44, i doubt they will appreciate me advertising for them. go there with an open mind and wallet and do what you can to actually carry out the emotions you type here.
i may be there, if you want a horse hauled anywhere worldwide and will pay the cost there will be someone there to help you. if you can't find anyone there you can call me, i'm very easy to find, all of my personal info is available on line thru links from this page. i have a horse here that was there a few months ago, i have more than i can feed comfortably now but have a truck and trailer and will donate my time to anyone willing to put their money where their keyboard is.