Fabric conditioner puts a thin coating of film on any fabric to make it soft and prevent static.. This affects the absorbency of the towel which is its primary purpose so it can't pick up water properly.
That's why Marks & Spencer put a label on their towels to recommend no fabric conditioner. Otherwise you'll be taking them back saying they don't dry you properly.
Purchased big bag of microfibre cloths from Costco think there were 36 cloths for about £15, they get washed at 30c in the regular laundry with Costco non-bio powder that's about £15 for a tub that does 400 washes. seems to work well...