Anything you may have purchased since 2009 would be cheaper than today's dollar. The price for raw copper material has shot up by over 72% in the last two months alone. Also, with fuel costs going wild currently, copper being the wire core, fuel for the manufacturing of the shielding and then trucking. The sad fact is the lights you are buying currently were more than likely manufactured one to two years ago. $3.99 is not incredibly high for the current market, however commodities pricing always spikes mid year (2nd & 3rd quarters) so the price MAY come down after that then spike again when demand steps up.
Like everyone will tell you go slow the first year then save for 12/26 and buy up all the lights you can, then eventually phase out the incans for LEDs as your display grows.