Thank you for posting your ques. on Trulia.com.
I can try looking for some comps in Holtville and help you out.
Please contact me with information on your mfg home so I can pull the profile and look for comps.
My contact info. is below.
Thank you and Good luck
Seven Six O' Real Estate
1275 West State St,
El Centro CA 92243
Dre # 01370527