Injecting my horse's SI joint made a dramatic "new horse" difference to him. He has fusing (now really fused) hocks that we have been injecting for years, but, with the benefit of heinsight, I think the general discomfort engendered by them doing their thing probably affected his posture and made him just cranky sore through that SI area. Then he got himself cast in a fence and went from having a not very good canter to having something that could only be described as a canter if you were being generous.
My vet used a new technique which didn't require the ultrasound guidance (they have a new vet in the practice who is from CSU/Littleton Large Animal who taught them all how to do this) and he literally came to my house and did it in my garage. Cost, $240.
This was back in Spetember. My horse finally has a big butt and pushing power behind, and is developing a really nice, balanced canter. He's also much more "through" and steadier in his carriage at the trot than we've been able to achieve in the past and has some semblance of a medium developing...
Couldn't be happier. Wish we'd done it earlier.
I'm still doing monthly pentosan, He's a teenager and has other creakies so it's an inexpensive way of keeping him lubed up.
Maybe when your fellow injured his hock he torqued something higher up too, or he may have got out of whack while moving oddly during his healing process, who knows? But it's worth discussing the SI with your vet.
To answer the OP's request - I love Flex Force HA liquid. It's very affordable and we have both young and old horses in our barn on it. I've seen great results and it is easily under $1/day. I just came across this review that agrees with me although they do suggest some more expensive alternatives as well . Anyway - I love it and wouldn't be without it.
Northern Virginia, 45 minutes east of paradise - 2 hrs during rush hour
I feed 2 scoops (60 g) which is about $1.5 a day but a baby would probably get 1 scoop which would be 75 cents.
BUT it has a basic vitamin and mineral set so may not be suitable it you are feeding other supplements or a fortified feed.
The other joint supplement I like is Absorbine Flex-max+
Both have worked well for me with a mare who has chronic inflammation in a hip that she injured.
"The mighty oak is a nut who stood its ground"
"...you'll never win Olympic gold by shaking a carrot stick at a warmblood..." see u at x