How to transfer LP to iMAC Computer


We have several LP recordings that are not available in CD format. We have an Onkyo turntable (old) and I would like to transfer my LP recordings to iTunes on my iMAC computer. Any suggestions on an easy way to do this would be greatly appreciated. Thanks.
hgeifman
Your suggestion above to use the Apogee Duet ADC/DAC to transfer my LP's to my iMAC (iTunes) looks great but the Apogee unit costs $500. I am looking for a less expensive solution. Can you recommend another unit that performs this function at less cost? Thanks
I have no direct experience with this myself, but gave one of these to my brother in-law and he seems to be very happy with it. Here you go - $99.