I can understand overlcocking as a hobby, but if you overclock because you need the performance then it's a much better solution to run a better part at stock speeds. Stock speeds provide cheaper, quieter surrounding components such as motherboard, case, heatsink, fans, powersupply etc. I would never suggest that somebody buys a cheaper part and overclock as opposed to a slightly more expensive part at stock speeds.
Overclocking only saves money if you don't have to buy or upgrade additional components to make up for extra heat and power.
Again, I understand most people overclock as a hobby, and these factors don't really influence their decision much.