Ekg's

I have seen EKG machines new/used which are put for sale...

If visual + audible heart sound is your fetish, there are few other tools which you can use.

Electronic watch / apple watch has rhythm monitor which can be viewed.

Heart beat ultrasound / vascular Doppler will give you audible sound..

If you have full Ultrasound machine, you can look at heart too . This one's expensive. Especially good portable one

Not the same as full EKG, but a good alternative..