Ugh! Distributors are kind of expensive
And if you take it off, you have to adjust your timing, and there simply is no reason to replace the whole unit. It is a wise idea to replace the distributor cap and rotor if it's been a while since you replaced it.
Main relay will most likely solve the problem, if not, then it's most likely the igniter unit. Also, check for another post in this forum, its titled "Sparkless & In the snow" or something like that...there is an explanation how to check if your igniter unit is ok. All you need is a basic multimeter to do the check.
Anyway, I'd keep the distributor (metallic massive part) and replace cap and rotor (if it's been a while) and resolder the relay first, and if it doesn't help - check the igniter.