So I was thinking about not only the how but the WHY of getting a lightsaber in the Rebellion Era. Unless your character's knowledgeable on the Jedi/Sith and, more importantly wants to be one, why would somebody with little-to-no knowledge of such weapons try to attain one?

One reason I came up with (which would depend on having a mentor or holocron, for education's sake) is that such a weapon can play to strengths not normally called upon in battle. From a mechanical view Brawn and Agility are the mainstays of fighting. Even though certain Talents use the other abilities, the applications are few and narrow, leaving your intelligent, charming bumbling cabbage leaf at a disadvantage in combat.

Now said person learns of a weapon that calls upon their great intellect, indomitable will or slick charm. A weapon that not only plays to your greatest strengths it allows you to hold your own in both melee and ranged combat. It can also be a powerful symbol.

'Not sure if I worded it well (popping in and out at work) but hope I did! It helped my group to reason why nascent Force users who at best know of Jedi as myth to justify lightsabers.

Of course, defeating an Imperial Inquisitor and taking his stuff is a good one, too!

stories. Luke heard of them before he met Obi Wan

Some will, some won't. And just because they have doesn't mean they'd chase down a lightsaber (with all the risks that entails). But knowing that such a weapon can be used with more than strength could motivate them to go after one.

It's not that they won't have heard of them or not want to be Jedi. My thoughts had to do with the less educated and/or those who don't want to follow a Force tradition.

Depending the kind of person that the characters are, but I'm sure in a period of time where sith and jedi are short on numbers, Much like holo tons, I'm sure that in the right market and ex jedis lightsaber may just rack up a lot of credit selling to the right person. Or maybe the player is a collector or historical aritfacts, seeing the fall of the jedi as a monumental occasion, and thus giving the lightsaber a some form value to a museum or private collector, there's heaps of reasons.

Part of "why a lightsaber?" could be to do with wanting to have a demonstrative statement that you're against what the Empire stands for.

The Empire by the Rebellion Era is regarded in most areas of the galaxy outside the Core Worlds as a bastion of tyranny and oppression, especially if you're not Human. The Jedi have plenty of myth around them, and even the most skeptical of beings will at least acknowledge that the Jedi were symbols of "better days" when the galactic government wasn't so oppressive. As Ben said in ANH, the Jedi Knights were the guardians of peace and justice in the Old Republic, and to some older sentients, they'd remember those days when the Jedi were, if not revered were at least respected, and generally known for being fair and just in their dealings with others, things that many ranking Imperials simply aren't .

It's also a statement of "yeah, you just picked a fight with the wrong person" to those the character finds themselves squaring off with. To draw from one of the earlier the SW:Rebels trailers, the scene when the Imperial Agent is ordering his stormtroopers to concentrate their fire on Kanan as he's assembling and activating his lightsaber, you can hear him mentally saying "oh crap!" as he's verbally saying "on the Jedi!" Granted, being to open with brandishing a lightsaber means you're metaphorically painting a pretty big target on your chest while shouting "come get some!" at the top of your lungs, but as Ben showed in ANH, being an expert with a lightsaber, a weapon that's noted to be difficult to properly wield and incredibly rare during that time frame, marks you as someone not to be trifled with.

The bit of fluff and character creation mechanics in the beta have a strong element of walking in the path of the Jedi to restore the Order or become a Jedi etc. Certainly this isn't forced on a player creating a character but there are multiple spots where this sort of character type is supported and mentioned - from Motivation, Career descriptions, and the holocron or mentor you can choose as a group resource, etc.

But it is an important question that a player should answer for their character.

when the empire wiped out all (most) of the jedi. what happened to their light sabers?

Maybe the storm troopers collected them for a) storage or b) disposal.

Maybe some jedi were brought down by bounty hunters who took their lightsabers as trophies

The Legends lore alludes to a tendency towards storage/collection, in a similar manner to how General Grievous took up the lightsabers of Jedi he'd slain.

In the Rogue Squadron novels, Corran Horn finds a repository of old Jedi stuff, including a lightsaber that holds special value to him, that the Emporer was keeping in what is effectively a warehouse.