I keep a spreadsheet of all my fiber purchases. The most I've ever paid for roving was $4.00 an ounce for some pima cotton. The least I've ever paid was 23 cents an ounce for some yucky, raw, uncleaned wool.
Over the past two or three years, I've bought 400 ounces of roving, spending a total of $462.43
The average price for the roving I've bought is $1.59 an ounce.