Here's what my "set" has in it,
I picked up a couple of 20" ratchets one S-K & one Napa for 25$ each off ebay. Local sale for a 36" Snap-on ratchet, 125$ (newer item).
Toptul 40" breaker bar, about 75$, I think. Titan has the same one for a little less. Broken Craftsman 18" breaker bar from my Dad, 0$
Snap-on 3/4 to 1/2 adapter 15$, ebay
Armstrong metric 12pt shallow set 22mm to 50mm IIRC, 95$ clearence off Sears site a couple years ago.
Inch set 15/16 to 2-1/4, missing 1-7/8, that I pieced together, some are newer, some are older. Not sure off hand how much, cost wise. Some sockets were free (from my Dad) some were 3-5$ each, others around 10-12$each.
16" 8" 4" extensions, around 50$ or thereabouts for all. Got some of ebay, other's at a Napa sale.
Check out Cripe distrubting, they have some pieces and sets in thier ebay store and website.
If you do go Harbor freight, do yourself a favor and get a decent ratchet to use. I've seen some made in china ones I would not trust not to break or strip a pawl.
The metric sizes will be the hardest to piece a set together with.
Inch sockets are very common and can be found second hand, usually 5-6$or so each.