Because SID Clones are cool and from time to time a new one appear, this List could be helpful to get an overview.
Feel free to add new or further Information where to buy/whatever... (Technically they are no real Clones they are emulations on microchips)
SwinSID http://www.swinkels.tvtom.pl/swinsid/ (DIY possible)
Arduino/Atmega based Replacement, cheap but simple
Mostly sold on ebay (about 15-20€)
SwinSID Ultimate
Improved SwinSiD
Full describtion https://www.polyplay.xyz/SwinSID-Ultimate
FPGASID
An FPGA based SID ;) further Infos: http://www.fpg