Of course it does more than just midi, but I think used Mk1 MonoMachines ($500) are great midi sequencers for the price.
Massive polyphony capabilities, and 3 LFOs x 6 tracks.
You get a quality digital synth as well, which you can choose not to use.
The 18 LFOs are shared between synth/fx tracks and midi tracks, but even when I use 5 LFOs on an aggressively patched single voice across two tracks on my Mk2+, I’m left with more LFOs for midi sequencing than the AK has all together.
It’s my only midi sequencer between Rytm, A4, and MnM.