Believe it or not, I found 3 Napoleon B. Price's - all union men:

Napoleon B. Price 63rd Regiment, Indiana Infantry Union

Napoleon B. Price 3rd Regiment, Kentucky Infantry Union

Napoleon B. Price 12th Regiment, Tennessee Cavalry Union

And one lonely Confederate:

Napoleon D. Price 38th Regiment, Virginia Infantry (Pittsylvania Regiment) Confederate

U.S. Civil War Soldiers, 1861-1865
Name: Napoleon B. Price
Side: Union
Regiment State/Origin: Tennesee
Regiment Name: 12 Tennessee Cavalry
Regiment Name Expanded: 12th Regiment, Tennessee Cavalry
Company: D
Rank In: Private
Rank In Expanded: Private
Rank Out: Private
Rank Out Expanded: Private
Film Number: M392 roll 12

1870 United States Federal Census
Name: Napoleon B Price
Estimated birth year: abt 1839
Age in 1870: 31
Birthplace: Tennessee
Home in 1870: Polk, Arkansas, Arkansas
Race: White
Gender: Male
Post Office: Mount Adams
He is listed as Merchant - Real Estate worth $1500 - Personal Worth $1000
Also in the household are:
Sarah W/F 47 Keeping House b.TN [his mother]
William M. W/M 22 Merchant b. TN
Mollie W/F 22 b. MS
Byron W/M 16 b. TN
Betty W/F 5 b. TN
Emma W/F 3 b. AK

1880 United States Federal Census
Name: Napoleon B. Price
Home in 1880: Keaton, Arkansas, Arkansas
Age: 41
Estimated birth year: abt 1839
Birthplace: Tennessee
Relation to head-of-household: Self (Head)
Spouse's name: Mollie E.
Father's birthplace: Virginia
Mother's name: Sarah A.
Mother's birthplace: Virginia
Occupation: Merchant
Marital Status: Married
Race: White
Gender: Male
Household Members: Name Age
Napoleon B. Price 41 Merchant
Mollie E. Price 32 wife Keeping House
Sarah A. Price 57 Mother
Bettie Price 14 daughter
Emma T. Price 13 daughter
Willie A. Price 6 son
Maude Price 3 daughter
Myrtle Price 2 daughter
Rachal Halfin 48 Boarder - Teacher
Byron Price 26 Brother - Book Keeping in store
Jefferson E. Trice 18 Cousin - Clerk in Store

Close by lives:
Wiliam M. Price 34 Merchant
Sally L. Price 25 wife Keeping House
Mable Price 8 daughter
William M. Price 6 son
Cecil C. Price 4 son
Herbert Price 2 son

1900 United States Federal Census
Name: William M Price
Home in 1900: McFall, Arkansas, Arkansas
Age: 54
Estimated birth year: abt 1846
Birthplace: Tennessee
Relationship to head-of-house: Head
Race: White
Occupation:
Household Members: Name Age
William M Price 54 Real Estate Agent
William Price 25 Real Estate Agent
Cecil C Price 23 Lawyer
Herbert L Price 21 at school
Robert E Price 19 at school
Byron Price 17 at school

Hope this helps.

JR