We just had 6 baby mini dashunds puppies. Three are dapple color is this rare??

Dapple, (also known as Merle) is NOT one of the recognised colors for Dachshunds and is a disqualification for showing.

Please get both dogs fixed as well as spay neuter the pups when they are old enough to prevent producing more of the defective color gene.

Dapple isn't rare. Please do not attempt to sell these puppies for more.

They are actually a recognized colour. As per the AKC:

"Dappled dachshunds-The dapple (merle) pattern is expressed as lighter-colored areas contrasting with the darker base color, which may be any acceptable color. Neither the light nor the dark color should predominate. Nose and nails are the same as for one- and two-colored Dachshunds. Partial or wholly blue (wall) eyes are as acceptable as dark eyes. A large area of white on the chest of a dapple is permissible."

Wow, didn't realise it was recognised in America, he in Aus Merles are very much frowned upon, being a Dane person I can't stand that particular color in any breed.

Merle is a dominant gene and is linked with defects such as blindness and deafness, hence the need for spaying the entire litter and the parents.

http://www.cbsweechis.com/id84.html

I have a merle Australian Shepherd, love her to bits.
And yes, ignorant breeders who don't understand the genetics of it can definitely bring out those flaws.