New chainrings aren't that expansive if you shop around. The Ultegra crank you have is a nice unit, so no need to throw out the baby with the bathwater. And the difference between the 9-speed and 10-speed stuff is mostly in the bottom-bracket tech used (octalink+cartridge for the 9-speed, external cups+cartridges for the 10-speed); the ring spacing is identical, as are the chainrings.

Great chainrings from FSA, SRAM/Truvativ, Stronglight, Vuelta or Shimano won't break the bank: you can often find them online for $25-40 a piece, which is a lot cheaper than a new equivalent to your Ultegra crankset. Shop around, do the math, and go for it!

And yes, chainrings can and do wear out: the tooth profiles often won't mesh with a new chain if the rings are too far gone (i.e. were trashed by a worn-out chain).