Is there any open and free data-set for digital ISI channels? I want to have a variety of ISI channels' taps, such as $h[k]$ here. Especially looking for BPSK channels.
Things like the good ole' GSM standard specify power delay profiles and a phase variation model. So, there you go, reference model delivered in the shape of a standard.
Other than that, if you're just looking for any ISI-inducing (i.e. frequency-selective) channel, why not use your favourite DSP framework to come up with a random FIR filter?
Also, a lot of frameworks do come with their own channel simulations; GNU Radio for example brings multiple channel models of varying realism in its gr-channel module.
I often find that students overestimate the complexity of actually measuring a channel impulse response to use it in their own channel simulations. Just send a PN, receive it at the same time, and use a correlation to find the impulse response; if your receiver and transmitter exhibit a frequency offset, you might need to try a couple of frequency shifts and use the one that gives the highest correlation coefficients.