I never cared for old slivers, but at this point, I don't like that they've completely changed the flavor of slivers. They should have called them something else.
Some of the more competitive stores are Yottaquest in College Hill and Game Swap in Mason. A more casual store is Rockin Rooster in Price Hill. They are also the cheapest in the area for prereleases.
I built my first deck (Korlash, now Kiku) out of stuff I already had with a handful of singles bought online. Spent the next four years upgrading and pimping it out. The only card from my original build that is still in use is my foil Sudden Death.
Also Land Equilibrium and Mana Vortex.