I always use a tap-tempo device in my rig, because I often work with a drummer &/or guitarist, & need to be able to get the sequencer running at the arbitrary tempo of a "real" instrument being played.
at the moment, I am having a problem with the octopus not correctly echo-ing midi stop commands when it is the clock slave. means I have to use a number of midi-merge boxes to achieve the ergonomics I’m after.
anyway.
the best, potentially cheap, tap-tempo device I can think of, besides the ploytech pedal, is any of the original korg electribe boxes (the ones without shiny metal tops & valves & all that). the tap tempo button is a nice big spongy rubber button that you can really pound on, & there’s a nice big tempo readout too. the clock is pretty stable.
I have also used (& am currently using) the electrix repeater as a master clock; the clock is a bit jittery sometimes (especially if the repeater is doing a lot of processing) but seems to be ok once a tempo is established. the korg was better at tracking changes, I reckon.
hth-
duncan.