As for when is the right time to buy one, I'd say the right time to buy one is when you feel it's worth your money. If you wait for computer hardware to get faster/cheaper you'll end up waiting forever
This is right on the money. When I bought my Vertex 3 a year ago, it was twice the price as they are selling for now. THAT'S THE SAME EXACT DRIVE, not even a new generation! Am I sore that I had to spend twice as much for the same drive? Of course, but that's water under the bridge. Do I regret buying an SSD? Absolutely not,
and I will never go back.
SSDs are the most significant and cost effective upgrade to overall responsiveness of ANY computer with at least a dual core processor. (see here
for examples) I would have no qualms about buying at their current pricing. 120GB may not seem like much, but when you've only got your OS, Programs, and Games on the SSD, you'd be amazed at how little space they actually consume. Videos/Music/Pictures take up a large portion of storage on any computer.
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Crosley D-25 Case Mod