The rubber shock absorber on my seat post is disintegrating. I have no complaints about the seat post (aside from its short life span), except a replacement from specialized is $249. Diameter is 27.2 mm. Can anyone recommend something good to replace it with. I don’t think I need the suspension. Let’s keep it under $100 as I’m hoping to get rid of this bike in the near future. Thanks!

the rubber provides no structural integrity to the seatpost. That’s what I would do

If that post only a the 'rubber' issue, I would still ride it.
But, looking closer at it, my eyes are seeing a stress crack starting at the lower section where the broken rubber/carbon connection is and runs down and over in an L shape.
I'd prolly take that post off as soon as possible.
Replacement - any 27.2 post will do, just a matter of what you prefer... setback, clamping method, etc. I prefer 2 bolt systems because micro-adjustment of seat rail angle is easy. I prefer fore-aft adjustment over side-by-side clamps.
I have a bunch of different Specialized CF posts most I like, one model has a single bolt using side-by-side clamps. Specialized even puts a note on the post to be sure to lubricate/grease the side clamps.
After a while they still make creaking noises... lubing only helps for a short time...
I prefer and have a bunch of the older model with Zertz insert - sturdy, good adjustment, I've got thousands of miles on them and they hold up, work well and never creak...
One is going on 20 years old and still no issues.
can be had 'used' in the usual used marketplaces online.
Ride On
Yuri
This is one I like best

This post/head, below, is the one which starts creaking on me, a month of riding after I lube the cups, as recommended... Don't remember if mine has Zertz... It's buried at the moment... I need to get rid of it...

Is the crack your seeing here? That appears to be an indentation in the post (on both sides). I think it’s reflecting the overhead light in the garage.

In the circle you drew, where the two ends are, the lower one has a 'point', just below that point is a crack in the 'rubber'? follow that down to where the crack leads to what appears could be a continuance into the post itself, and if so it would appear to curve down on the post... Again, 'appear' - from a photo this is only supposition. 1st hand inspection would be needed.
There are also 'chips', seen as small white marks which seem to follow that crack line, as you look further... Again, 'appear'...
The insert you call 'rubber' is clearly more brittle than a rubber compound. It may have elastomer properties, but fracturing as seen is not common to most elastomers, unless there's been some change to the material. The rib forms an I-beam type structure with the post, to limit flex.
That rib is there to support the carbon fiber arch of the post, and limit the 'flex - otherwise there's be a good possibility the post would assplode if put under a sudden, hard load.
My deduction is that the 'rib' assploded under a load (or multiple loads), with the possibility of some further damage starting on the actual Carbon Fiber.
Would it be presumptuous to ask how much you weigh?
Did you get the post or the bike New or Used? Is there a possibility that the seatpost already had some damage and you hadn't noted it prior to the rib collapsing? All worth asking/considering.
I'm not familiar with this post, so conjecture of what appears. But I'd be looking deeper if I was putting my butt on top that.
Ride On
Yuri

I have one I removed from my Roubaix, still in excellent shape. PM me if interested

I'd go for the Canyon S15 / Ergon CF Allroad Pro. I haven't used it but I believe it offers more movement, and more lateral movement, than most seatposts.

hello- I realize this is pretty late, but I need this rubber damper as it has now disintegrated on my Roubaix as well. Any chance you still have it laying around? Thanks

Sorry, sold after my last post. I'd check eBay, they seem to pop up regularly.