Manufactured or Mobile homes do not qualify for conventional financing. There are fewer lenders and the terms are a bit more restrictive. Some issues will vary depending on if the house is in a park where you rent the space or if it's placed on land and is a package deal.
Talk to some local mortgage brokers to see what they have to offer. US Bank was still open to mobile homes the last time I checked.
One last thought, the reason the terms are more restrictive, higher down payment, shorter terms, higher rates, are because historically manufactured/mobile homes do not hold their value as well as homes built on the lot, also called "Stick Built" homes. For the lender, their investment is riskier and so they offset the risk with greater security for them.
Before you decide, consider a conventional home, condo or townhouse, you may have more options and find out they are more affordable than they appear when the financing options are considered.