A 2way in many ways is very simlar to a locked diff, so if you dont want a locked diff I would suggest 1.5way.
Brand new Kaaz diffs can be had for $1050 delivered, and they include the bearings. All you have to do is get it put into the housing.
2nd hand mechnicals go for about 800-1000, but usually in housings already so just bolt in, so the question is, do you want to spend another 200-400 to get a brand newie?
But with the brand new diff you do have to do break in, change oil a lot, etc. But you do have peace of mind.