I’m rolling about on a £12.17 (27.2) Carbon post from that there China (via fleabay), Definitely Cheap, finish was all right, obviously not the lightest available, seems comfy with a Selle Italia XO on top (also cheap), most importantly though it seems to suit my arse, longest period of use thus far was a 63 mile ride on Sunday and it was was nice and comfy throughout. but it’s early days, It will most probably snap and stab me in the arse cheek at some point, But if you want properly cheap it can be had…
I think a lot of it comes down to what Shorts/pad you use as well though too… Tyres can help quite a bit
Thinking about it further it’s a bit of a Heirachy innit:
-Tyres: Volume and pressure
-Frame: Materials and configuration, (Vibration Damping Vs Stiffness)
-Seatpost: material and configuration (As Above really)
-Seat: Rail materials, shape, padding
-Shorts: Padding, layers/shape
The last two are arguably the most important as if a seat/pad isn’t quite right could negate all the benefits from the rest of it…
Not sure I’d expect a change of seat post alone to fix things…