It depends upon size, area, and going rate. Around here figure $7000 to $10000 and up for a basement. Septic depending on type and style and size $1000 to $3000 or more. Ask your manufactured home dealer except sometimes they sub things out plus a percentage. I am sure you are paying them to set it up anyway.
Contact your local basement contractor. If you don't know one, drive out to a new subdivision and find one working. Most builders around here sub basements out. Contact a plumber experienced in septic systems for a septic system estimate. Some backhoe/dirt contractors do them too.