check your local mountain's events calendars a few times a year there will probably be a demo event. usually these are larger manufacturers (e.g., Burton) or local companies (rome in the northeast, mervin in the pac/nw, etc.) or smaller local brands.
Otherwise ask around at your local shops and see if they do any demos or if they rent in-season gear. none of the shops near me do this but I have heard of them so maybe you'd pay $25 to rent a new-ish board for a day, etc.
use your own boots 99% of the time and probably your own bindings, too, unless you're lucky enough to get to a private/industry demo event where you could check out all the gear.