www.wcdetail.com is where I get mine from they are great for the price. I use cheaper mf towels like from wally world/AZ to clean rims, wheels, door jams, ect, ect.
Also www.exceldetail.com has some great towels pretty cheap and way better then store bought towels.
Sonus Detailing Towel Kit
This kit has every towel you will need and is a perfect "starterkit".
It comes with 2 ultimate detailing towels(Great for cleaning glass)
2 Drying towels
2 Buffing towels
2 Polishing towels
and a bottle of Micro fiber wash solution.